wait event docs

The wait event information in PostgreSQL is very helpful for
troubleshooting.  I always reference the PostgreSQL docs first, and when
people ask me about wait events that where I send them first.  The list
of wait events there is comprehensive, but the descriptions are a bit
terse and often use vocabulary that requires some familiarity with the
internals to understand.

AWS created some wait event documentation for Aurora with PostgreSQL
compatibility which takes a slightly different approach.  It's a lot
more words... but it tries to give useful suggestions about how to
improve (or fix) the system when a particular wait event is encountered.

https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraPostgreSQL.Reference.html#AuroraPostgreSQL.Reference.Waitevents

Something like this would be really valuable for open source PostgreSQL
too.  While somebody's personal blog is one solution, it doesn't seem
wholly inappropriate to live on a community resource.  I'd be happy to
seed the content and continue making updates it as I regularly helping
people solve problems on open source community PostgreSQL (and hopefully
others contribute too).

Could we create a new wiki page as a starting point, and we could draft
up and maintain something there for a little while?  Maybe a place like
https://wiki.postgresql.org/wiki/Wait_Events ?

If it does turn out to be useful for a lot of people then maybe it could
even get into the PG docs someday.  :)

-Jeremy

P.S. my wiki username is "Jer"  https://wiki.postgresql.org/wiki/User:Jer

--
Jeremy Schneider
Database Engineer
Amazon Web Services