Fix broken/redirected links, moving to HTTPS where possible. (#20557)

docs/getting-started/accessibility.md

@@ -47,7 +47,7 @@ Note that this bug will also affect any other in-page links your site may be usi
 
 When nesting headings (`<h1>` - `<h6>`), your primary document header should be an `<h1>`. Subsequent headings should make logical use of `<h2>` - `<h6>` such that screen readers can construct a table of contents for your pages.
 
-Learn more at [HTML CodeSniffer](http://squizlabs.github.io/HTML_CodeSniffer/Standards/Section508/) and [Penn State's Accessability](http://accessibility.psu.edu/headings).
+Learn more at [HTML CodeSniffer](https://squizlabs.github.io/HTML_CodeSniffer/Standards/Section508/) and [Penn State's Accessability](http://accessibility.psu.edu/headings).
 
 ## Additional resources
 

docs/getting-started/browsers-devices.md

@@ -172,7 +172,7 @@ See [this StackOverflow question](https://stackoverflow.com/questions/6771258/wh
 
 ## Internet Explorer 10 in Windows Phone 8
 
-Internet Explorer 10 in Windows Phone 8 versions older than [Update 3 (a.k.a. GDR3)](http://blogs.windows.com/windows_phone/b/wpdev/archive/2013/10/14/introducing-windows-phone-preview-for-developers.aspx) doesn't differentiate **device width** from **viewport width** in `@-ms-viewport` at-rules, and thus doesn't properly apply the media queries in Bootstrap's CSS. To address this, you'll need to **include the following JavaScript to work around the bug**.
+Internet Explorer 10 in Windows Phone 8 versions older than [Update 3 (a.k.a. GDR3)](https://blogs.windows.com/buildingapps/2013/10/14/introducing-windows-phone-preview-for-developers/) doesn't differentiate **device width** from **viewport width** in `@-ms-viewport` at-rules, and thus doesn't properly apply the media queries in Bootstrap's CSS. To address this, you'll need to **include the following JavaScript to work around the bug**.
 
 {% highlight js %}
 // Copyright 2014-2015 The Bootstrap Authors
@@ -189,7 +189,7 @@ if (navigator.userAgent.match(/IEMobile\/10\.0/)) {
 }
 {% endhighlight %}
 
-For more information and usage guidelines, read [Windows Phone 8 and Device-Width](http://timkadlec.com/2013/01/windows-phone-8-and-device-width/).
+For more information and usage guidelines, read [Windows Phone 8 and Device-Width](https://timkadlec.com/2013/01/windows-phone-8-and-device-width/).
 
 As a heads up, we include this in all of Bootstrap's documentation and examples as a demonstration.
 

docs/getting-started/build-tools.md

@@ -20,7 +20,7 @@ To use our Gruntfile and run our documentation locally, you'll need a copy of Bo
 When completed, you'll be able to run the various Grunt commands provided from the command line.
 
 [install-ruby]: https://www.ruby-lang.org/en/documentation/installation/
-[gembundler]: http://bundler.io/
+[gembundler]: https://bundler.io/
 
 ## Using Grunt
 
@@ -30,7 +30,7 @@ Our Gruntfile includes the following commands and tasks:
 | --- | --- |
 | `grunt` | Run `grunt` to run tests locally and compile the CSS and JavaScript into `/dist`. **Uses [Sass](http://sass-lang.com/), [Autoprefixer][autoprefixer], and [UglifyJS](http://lisperator.net/uglifyjs/).** |
 | `grunt dist` | `grunt dist` creates the `/dist` directory with compiled files. **Uses [Sass](http://sass-lang.com/), [Autoprefixer][autoprefixer], and [UglifyJS](http://lisperator.net/uglifyjs/).** |
-| `grunt test` | Runs [scss-lint](https://github.com/brigade/scss-lint), [ESLint](http://eslint.org/) and [QUnit](http://qunitjs.com/) tests headlessly in [PhantomJS](http://phantomjs.org/) (used for CI). |
+| `grunt test` | Runs [scss-lint](https://github.com/brigade/scss-lint), [ESLint](http://eslint.org/) and [QUnit](https://qunitjs.com/) tests headlessly in [PhantomJS](http://phantomjs.org/) (used for CI). |
 | `grunt docs` | Builds and tests CSS, JavaScript, and other assets which are used when running the documentation locally via `jekyll serve`. |
 | `grunt watch` | This is a convenience method for watching just Sass files and automatically building them whenever you save. |
 
@@ -57,7 +57,7 @@ Running our documentation locally requires the use of Jekyll, a decently flexibl
 2. From the root `/bootstrap` directory, run `bundle exec jekyll serve` in the command line.
 3. Open <http://localhost:9001> in your browser, and voilà.
 
-Learn more about using Jekyll by reading its [documentation](http://jekyllrb.com/docs/home/).
+Learn more about using Jekyll by reading its [documentation](https://jekyllrb.com/docs/home/).
 
 ## Troubleshooting
 

docs/getting-started/download.md

@@ -37,7 +37,7 @@ Bootstrap's `package.json` contains some additional metadata under the following
 
 ### RubyGems
 
-Install Bootstrap in your Ruby apps using [Bundler](http://bundler.io/) (**recommended**) and [RubyGems](https://rubygems.org/) by adding the following line to your [`Gemfile`](http://bundler.io/gemfile.html):
+Install Bootstrap in your Ruby apps using [Bundler](https://bundler.io/) (**recommended**) and [RubyGems](https://rubygems.org/) by adding the following line to your [`Gemfile`](https://bundler.io/gemfile.html):
 
 {% highlight ruby %}
 gem 'bootstrap', '~> 4.0.0.alpha3'
@@ -67,7 +67,7 @@ $ composer require twbs/bootstrap:{{ site.current_version }}
 
 ### Bower
 
-Install and manage Bootstrap's Sass and JavaScript using [Bower](http://bower.io).
+Install and manage Bootstrap's Sass and JavaScript using [Bower](https://bower.io).
 
 {% highlight bash %}
 $ bower install bootstrap#v{{ site.current_version }}

docs/getting-started/flexbox.md

@@ -40,7 +40,7 @@ If you're familiar with modifying variables in Sass—or any other CSS preproces
 2. Change it from `false` to `true`.
 3. Recompile, and done!
 
-Alternatively, if you don't need the source Sass files, you may swap the default Bootstrap compiled CSS with the compiled flexbox variation. [Head to the download page]({{ site.baseurl }}/getting-started/download) for more information.
+Alternatively, if you don't need the source Sass files, you may swap the default Bootstrap compiled CSS with the compiled flexbox variation. [Head to the download page]({{ site.baseurl }}/getting-started/download/) for more information.
 
 ## Browser support
 

docs/getting-started/introduction.md

@@ -17,7 +17,7 @@ Here's how to quickly get started with the Bootstrap CDN and a template starter
 
 ## Quick start
 
-Looking to quickly add Bootstrap to your project? Use the Bootstrap CDN, provided for free by the folks at MaxCDN. Using a package manager or need to download the source files? [Head to the downloads page.]({{ site.baseurl }}/getting-started/download)
+Looking to quickly add Bootstrap to your project? Use the Bootstrap CDN, provided for free by the folks at MaxCDN. Using a package manager or need to download the source files? [Head to the downloads page.]({{ site.baseurl }}/getting-started/download/)
 
 Copy-paste the stylesheet `<link>` into your `<head>` before all other stylesheets to load our CSS.
 
@@ -40,7 +40,7 @@ And that's it—you're on your way to a fully Bootstrapped site. If you're at al
 Be sure to have your pages set up with the latest design and development standards. That means:
 
 * Using an HTML5 doctype
-* Forcing Internet Explorer to use its latest rendering mode ([read more](http://stackoverflow.com/q/6771258))
+* Forcing Internet Explorer to use its latest rendering mode ([read more](https://stackoverflow.com/questions/6771258/what-does-meta-http-equiv-x-ua-compatible-content-ie-edge-do))
 * And, utilizing the viewport meta tag.
 
 Put it all together and your pages should look like this:
@@ -68,7 +68,7 @@ Put it all together and your pages should look like this:
 </html>
 {% endhighlight %}
 
-That's all you need for overall page requirements. Visit the [Layout docs]({{ site.baseurl }}/layout/overview) or [our official examples]({{ site.baseurl }}/examples/) to start laying out your site's content and components.
+That's all you need for overall page requirements. Visit the [Layout docs]({{ site.baseurl }}/layout/overview/) or [our official examples]({{ site.baseurl }}/examples/) to start laying out your site's content and components.
 
 ## Important globals
 
@@ -115,7 +115,7 @@ Learn more about [box model and sizing at CSS Tricks](https://css-tricks.com/box
 
 ### Normalize.css
 
-For improved cross-browser rendering, we use [Normalize.css](http://necolas.github.io/normalize.css/) to correct small inconsistencies across browsers and devices. We further build on this with our own, slightly more opinionated styles with [Reboot]({{ site.baseurl }}/content/reboot/).
+For improved cross-browser rendering, we use [Normalize.css](https://necolas.github.io/normalize.css/) to correct small inconsistencies across browsers and devices. We further build on this with our own, slightly more opinionated styles with [Reboot]({{ site.baseurl }}/content/reboot/).
 
 ## Community