Fix some typos, grammar and style in docs and comments

Michael Paquier <michael@paquier.xyz>

Commit: c7a4fc3dd001646d5938687ad59ab84545d5d043
Author: Michael Paquier <michael@paquier.xyz>
Date: 2021-02-24T07:14:13Z
Releases: 9.6.22
Fix some typos, grammar and style in docs and comments

The portions fixing the documentation are backpatched where needed.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20210210235557.GQ20012@telsasoft.com
backpatch-through: 9.6

Files

Documentation touched

Discussion