Merge commit '9b0050e9aabe4be65c78ccf292a348f309d50ccd' as 'docs'

```
git subtree add --prefix=docs/ https://github.com/gohugoio/hugoDocs.git master --squash
```

Closes #11925

docs/content/en/functions/os/Getenv.md

@@ -0,0 +1,61 @@
+---
+title: os.Getenv
+description: Returns the value of an environment variable, or an empty string if the environment variable is not set.
+categories: []
+keywords: []
+action:
+  aliases: [getenv]
+  related:
+    - functions/os/FileExists
+    - functions/os/ReadDir
+    - functions/os/ReadFile
+    - functions/os/Stat
+  returnType: string
+  signatures: [os.Getenv VARIABLE]
+aliases: [/functions/getenv]
+toc: true
+---
+
+## Security
+
+By default, when using the `os.Getenv` function Hugo allows access to:
+
+- The `CI` environment variable
+- Any environment variable beginning with `HUGO_`
+
+To access other environment variables, adjust your site configuration. For example, to allow access to the `HOME` and `USER` environment variables:
+
+{{< code-toggle file=hugo >}}
+[security.funcs]
+getenv = ['^HUGO_', '^CI$', '^USER$', '^HOME$']
+{{< /code-toggle >}}
+
+Read more about Hugo's [security policy].
+
+[security policy]: /about/security-model/#security-policy
+
+## Examples
+
+```go-html-template
+{{ getenv "HOME" }} → /home/victor
+{{ getenv "USER" }} → victor
+```
+
+You can pass values when building your site:
+
+```sh
+MY_VAR1=foo MY_VAR2=bar hugo
+
+OR
+
+export MY_VAR1=foo
+export MY_VAR2=bar
+hugo
+```
+
+And then retrieve the values within a template:
+
+```go-html-template
+{{ getenv "MY_VAR1" }} → foo
+{{ getenv "MY_VAR2" }} → bar
+```