docs: adding documentation writing guidelines (cosmos#9366)

* docs: adding documentation writing guidelines

* update

* Apply suggestions from code review

Co-authored-by: Marie Gauthier <marie.gauthier63@gmail.com>
Co-authored-by: Ryan Christoffersen <12519942+ryanchristo@users.noreply.github.com>

Co-authored-by: likhita-809 <78951027+likhita-809@users.noreply.github.com>
Co-authored-by: Marie Gauthier <marie.gauthier63@gmail.com>
Co-authored-by: Ryan Christoffersen <12519942+ryanchristo@users.noreply.github.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>