Document that char() ignores spaces only in non-pattern comparisons

A private email I received indicated that our documentation about
ignoring trailing spaces in CHAR() comparisons was slightly inaccurate.
I have update our docs to indicate it is only non-pattern comparisons
that ignore spaces with CHAR(). Applied doc patch attached.

--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +