docs: adding documentation writing guidelines (#9366)

* docs: adding documentation writing guidelines

* update

* Apply suggestions from code review

Co-authored-by: Marie Gauthier <[email protected]>
Co-authored-by: Ryan Christoffersen <[email protected]>

Co-authored-by: likhita-809 <[email protected]>
Co-authored-by: Marie Gauthier <[email protected]>
Co-authored-by: Ryan Christoffersen <[email protected]>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>