Remove web ide beta flag from docs and update

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)
+> Brought to [GitLab CE][ce] in 10.7.
+The Web IDE makes it faster and easier to contribute changes to your projects
+by providing an advanced editor with commit staging.
 ## Open the Web IDE
-Once enabled, the Web IDE can be opened when viewing a file, from the
-repository file list.
+The Web IDE can be opened when viewing a file, from the repository file list,
+and from merge requests.
 ![Open Web IDE](img/open_web_ide.png)
@@ -32,4 +21,14 @@ the 'Commit Button'.
 ![Commit changes](img/commit_changes.png)
+## Comparing changes
+
+Before you commit your changes, you can compare them with the previous commit
+by switching to the review mode or selecting the file from the staged files
+list.
+
+An additional review mode is available when you open a merge request, which
+shows you a preview of the merge request diff if you commit your changes.
+
 [ee]: https://about.gitlab.com/products/
+[ce]: https://about.gitlab.com/products/