[docs] Clean up squashing section

Author: patricklodder

CONTRIBUTING.md

@@ -79,8 +79,8 @@ Use the pull request that is already open (or was created earlier) to amend
 changes. This preserves the discussion and review that happened earlier for
 the respective change set.
 
-The length of time required for peer review is unpredictable and will vary from
-pull request to pull request.
+The length of time required for peer review is unpredictable and will vary
+between pull requests.
 
 
 ## Pull Request Philosophy