Release v5.3.0-alpha1 (#37661)

* Bump version to 5.3.0-alpha1

* Dist

* Add docs versions updates

* Update note in homepage hero

Co-authored-by: Mark Otto <markdotto@gmail.com>

site/content/docs/5.3/components/close-button.md

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+---
+layout: docs
+title: Close button
+description: A generic close button for dismissing content like modals and alerts.
+group: components
+toc: true
+---
+
+## Example
+
+Provide an option to dismiss or close a component with `.btn-close`. Default styling is limited, but highly customizable. Modify the Sass variables to replace the default `background-image`. **Be sure to include text for screen readers**, as we've done with `aria-label`.
+
+{{< example >}}
+<button type="button" class="btn-close" aria-label="Close"></button>
+{{< /example >}}
+
+## Disabled state
+
+Disabled close buttons change their `opacity`. We've also applied `pointer-events: none` and `user-select: none` to preventing hover and active states from triggering.
+
+{{< example >}}
+<button type="button" class="btn-close" disabled aria-label="Close"></button>
+{{< /example >}}
+
+## Dark variant
+
+{{< callout info >}}
+**Heads up!** As of v5.3.0, the `.btn-close-white` class is deprecated. Instead, use `data-bs-theme="dark"` to change the color mode of the close button.
+{{< /callout >}}
+
+Add `data-bs-theme="dark"` to the `.btn-close`, or to its parent element, to invert the close button. This uses the `filter` property to invert the `background-image` without overriding its value.
+
+{{< example class="bg-dark" >}}
+<div data-bs-theme="dark">
+  <button type="button" class="btn-close" aria-label="Close"></button>
+  <button type="button" class="btn-close" disabled aria-label="Close"></button>
+</div>
+{{< /example >}}
+
+## Sass
+
+### Variables
+
+{{< scss-docs name="close-variables" file="scss/_variables.scss" >}}