chore(docs): use correct comment syntax (angular#177)

Fixes angular#176

Author: filipesilva

README.md

@@ -36,8 +36,8 @@ cd my-proj
 We have no intention of updating the source on `angular/quickstart`.
 Discard everything "git-like" by deleting the `.git` folder.
 ```bash
-rm -rf .git  // non-Windows
-rd .git /S/Q // windows
+rm -rf .git  # non-Windows
+rd .git /S/Q # windows
 ```
 
 ### Create a new git repo