Re: clean up docs for v12 - Mailing list pgsql-hackers

I made bunch of changes based on Andres' review and I split some more
indisputable 1 line changes from the large commit, hoping it will be easier to
review both.  Several bits and pieces of the patch have been applied piecemeal,
but I was hoping to avoid continuing to do that.

I think at least these are also necessary.
v5-0002-Say-it-more-naturally.patch
                                             
 
v5-0010-spelling-and-typos.patch
                                             
 

I suggest to anyone reading to look at the large patch last, since its changes
are longer and less easy to read.  Many of the changes are intended to improve
the text rather than to fix a definite error.

Justin