Add gin_fuzzy_search_limit to postgresql.conf.sample.
Add gin_fuzzy_search_limit to postgresql.conf.sample.

This was forgotten in 8a3631f (commit that originally added the parameter)
and 0ca9907 (commit that added the documentation later that year).

Back-patch to all supported versions.

greenplum-db/gpdb,ashwinstar/gpdb,adam8157/gpdb,lisakowen/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,adam8157/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,xinzweb/gpdb,lisakowen/gpdb,lisakowen/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,lisakowen/gpdb,50wu/gpdb,50wu/gpdb,adam8157/gpdb,adam8157/gpdb,jmcatamney/gpdb,xinzweb/gpdb,50wu/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,xinzweb/gpdb,50wu/gpdb,xinzweb/gpdb,xinzweb/gpdb,ashwinstar/gpdb,lisakowen/gpdb,ashwinstar/gpdb,adam8157/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,50wu/gpdb,lisakowen/gpdb,greenplum-db/gpdb,adam8157/gpdb,50wu/gpdb,jmcatamney/gpdb,xinzweb/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,50wu/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb