Update contributing guidelines; some issues may be OS specific (#66289)

CONTRIBUTING.md

@@ -37,7 +37,6 @@ If you find your issue already exists, make relevant comments and add your [reac
 * 👍 - upvote
 * 👎 - downvote
 
-
 If you cannot find an existing issue that describes your bug or feature, create a new issue using the guidelines below.
 
 ### Writing Good Bug Reports and Feature Requests
@@ -52,7 +51,9 @@ The built-in tool for reporting an issue, which you can access by using `Report
 
 Please include the following with each issue:
 
-* Version of VS Code
+* Version of VS Code  
+
+* Your operating system  
 
 * List of extensions that you have installed