Backport Web IDE docs to gitlab-ce

doc/user/project/index.md

@@ -45,6 +45,7 @@ and time spent on
 templates for issue and merge request description fields for your project
 - [Slash commands (quick actions)](quick_actions.md): Textual shortcuts for
 common actions on issues or merge requests
+- [Web IDE](web_ide/index.md)
 **GitLab CI/CD:**

doc/user/project/web_ide/index.md

+# Web IDE
+
+> Introduced in [GitLab Ultimate][ee] 10.4.
+
+> **Warning:** Web IDE is in **Beta**. For the latest updates, check the
+> associated [epic](https://gitlab.com/groups/gitlab-org/-/epics/26).
+
+The Web IDE editor makes it faster and easier to contribute changes to your
+projects by providing an advanced editor with commit staging.
+
+## Enable the Web IDE
+
+While in the early stages of the Beta, access to the Web IDE is by opting in.
+
+To enable the Web IDE, click on your profile image in the top right corner and
+navigate to **Settings > Preferences**, check **Enable Web IDE** and save.
+
+![Enable Web IDE](img/enable_web_ide.png)
+
+## Open the Web IDE
+
+Once enabled, the Web IDE can be opened when viewing a file, from the
+repository file list.
+
+![Open Web IDE](img/open_web_ide.png)
+
+## Commit changes
+
+Changed files are shown on the right in the commit panel. All changes are
+automatically staged. To commit your changes, add a commit message and click
+the 'Commit Button'.
+
+![Commit changes](img/commit_changes.png)
+
+[ee]: https://about.gitlab.com/products/