minor #4514 [Contributing][Documentation] typo fix (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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[Contributing][Documentation] typo fix

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

Commits
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fb1dd1f typo fix

contributing/documentation/overview.rst

@@ -170,7 +170,7 @@ Now you can **sync your fork** by executing the following command:
     $ git merge upstream/2.3
 
 This command will update the ``2.3`` branch, which is the one you used to
-create the new branch for your changes. If have used another base branch,
+create the new branch for your changes. If you have used another base branch,
 e.g. ``master``, replace the ``2.3`` with the appropriate branch name.
 
 Great! Now you can proceed by following the same steps explained in the previous