Update README.rst (apache#42941)

grammar update for clarity 😄 👍

docs/README.rst

@@ -20,7 +20,7 @@ Documentation
 
 This directory contains documentation for the `Apache Airflow project <https://airflow.apache.org/docs/>`__ and the providers packages that are closely related to it. You can contribute to the Airflow Docs in the same way and for the same reasons as contributing code; Docs contributions that improve existing content, fix bugs, and create new content are welcomed and encouraged.
 
-This README gives an overview about how Airflow uses `Sphinx <https://www.sphinx-doc.org/>`__ to write and build docs. It also includes instructions for how to make Docs changes locally or with the GitHub UI.
+This README gives an overview about how Airflow uses `Sphinx <https://www.sphinx-doc.org/>`__ to write and build docs. It also includes instructions on how to make Docs changes locally or with the GitHub UI.
 
 Development documentation preview
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