Merge pull request #17032 from tgxworld/update_contributing_guide

[CI SKIP] Improve force push note.

guides/source/contributing_to_ruby_on_rails.md

@@ -563,17 +563,17 @@ been updated.
 
 Sometimes you will be asked to make some changes to the code you have
 already committed. This can include amending existing commits. In this
-case git will not allow you to push the changes as the pushed version
-and local version does not match. Instead of opening new pull request,
-you can force push to your branch on Github like described earlier in
+case Git will not allow you to push the changes as the pushed branch
+and local branch do not match. Instead of opening a new pull request,
+you can force push to your branch on GitHub as described earlier in
 squashing commits section:
 
 ```bash
 $ git push origin my_pull_request -f
 ```
 
-This will update the branch on Github with your new code and
-Github will take care of updating the pull request with new code.
+This will update the branch and pull request on GitHub with your new code. Do
+note that using force push may result in commits being lost on the remote branch; use it with care.
 
 
 ### Older Versions of Ruby on Rails