Log Message:
-----------
Add note that the logging collector can block backends in high load situations.
Modified Files:
--------------
pgsql/doc/src/sgml:
config.sgml (r1.225 -> r1.226)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml?r1=1.225&r2=1.226)