Re: doc - improve description of default privileges

Some thoughts:

We should keep the GRANT reference page about GRANT.  There is a section
about Privileges in the Data Definition chapter, which we could use to
expand on general concepts.

The ALTER DEFAULT PRIVILEGES reference page would be another place this
could be put.

The Owner column is redundant, because it's always all applicable
privileges.  (Having this column would give the impression that it's not
always all privileges, so it would be confusing.)

Privileges should be listed using their full name (e.g., "SELECT"), not
their internal abbreviation letter.

The psql commands seem out of place here.  If you want to learn about
how to use psql, you can go to the psql documentation.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services