Merge branch 'docs-gfm-cleanup' into 'master'

Docs: GFM Doc Refactor

Closes #12681, #52394, #56148, #58676, #50138, and #52250

See merge request gitlab-org/gitlab-ce!27265

doc/user/project/settings/index.md

@@ -18,7 +18,7 @@ Adjust your project's name, description, avatar, [default branch](../repository/
 ![general project settings](img/general_settings.png)
-The project description also partially supports [standard markdown](../../markdown.md#standard-markdown). You can use [emphasis](../../markdown.md#emphasis), [links](../../markdown.md#links), and [line-breaks](../../markdown.md#line-breaks) to add more context to the project description.
+The project description also partially supports [standard markdown](../../markdown.md#standard-markdown-and-extensions-in-gitlab). You can use [emphasis](../../markdown.md#emphasis), [links](../../markdown.md#links), and [line-breaks](../../markdown.md#line-breaks) to add more context to the project description.
 ### Sharing and permissions