Added information about syntax highlighting in Web IDE. Fixes gitlab-org/gitlab-ce#53571

doc/user/project/web_ide/index.md

@@ -22,6 +22,27 @@ searching. The file finder is launched using the keyboard shortcut `Command-p`,
 `Control-p`, or `t` (when editor is not in focus). Type the filename or
 file path fragments to start seeing results.
+## Syntax highligting
+
+As expected from an IDE, syntax highlighting for many languages within 
+the Web IDE will make your direct editing even easier.
+
+The Web IDE currently provides:
+
+- Basic syntax colorization for a variety of programming, scripting and markup 
+languages such as XML, PHP, C#, C++, Markdown, Java, VB, Batch, Python, Ruby 
+and Objective-C.  
+- IntelliSense and validation support (displaying errors and warnings, providing 
+smart completions, formatting, and outlining) for some languages. For example: 
+TypeScript, JavaScript, CSS, LESS, SCSS, JSON and HTML. 
+
+Because the Web IDE is based on the [Monaco Editor](https://microsoft.github.io/monaco-editor/), 
+you can find a more complete list of supported languages in the 
+[Monaco languages](https://github.com/Microsoft/monaco-languages) repository.  
+
+NOTE: **Note:**
+Single file editing is based on the [Ace Editor](https://ace.c9.io).
+
 ## Stage and commit changes
 After making your changes, click the Commit button in the bottom left to