Thread: pgsql-server: Document background writer control parameters, do some

Log Message:
-----------
Document background writer control parameters, do some editorial work
on other recent changes in runtime parameter list.

Modified Files:
--------------
    pgsql-server/doc/src/sgml:
        runtime.sgml (r1.273 -> r1.274)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/runtime.sgml.diff?r1=1.273&r2=1.274)
    pgsql-server/src/backend/utils/misc:
        postgresql.conf.sample (r1.123 -> r1.124)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/utils/misc/postgresql.conf.sample.diff?r1=1.123&r2=1.124)