Fix stray sentence fragment in shared_preload_libraries documentation
Fix stray sentence fragment in shared_preload_libraries documentation

The introduction in the Shared Library Preloading section already
instructs the user to separate multiple library names with commas, so
just remove the fragment from here.

Author: Dagfinn Ilmari Mannsåker

greenplum-db/gpdb,zeroae/postgres-xl,yazun/postgres-xl,adam8157/gpdb,adam8157/gpdb,xinzweb/gpdb,jmcatamney/gpdb,50wu/gpdb,50wu/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,lisakowen/gpdb,lisakowen/gpdb,50wu/gpdb,oberstet/postgres-xl,adam8157/gpdb,lisakowen/gpdb,greenplum-db/gpdb,lisakowen/gpdb,techdragon/Postgres-XL,greenplum-db/gpdb,ovr/postgres-xl,lisakowen/gpdb,50wu/gpdb,Postgres-XL/Postgres-XL,ashwinstar/gpdb,yazun/postgres-xl,jmcatamney/gpdb,oberstet/postgres-xl,greenplum-db/gpdb,yazun/postgres-xl,zeroae/postgres-xl,oberstet/postgres-xl,50wu/gpdb,ashwinstar/gpdb,ovr/postgres-xl,Postgres-XL/Postgres-XL,yazun/postgres-xl,50wu/gpdb,ashwinstar/gpdb,lisakowen/gpdb,pavanvd/postgres-xl,techdragon/Postgres-XL,techdragon/Postgres-XL,oberstet/postgres-xl,Postgres-XL/Postgres-XL,Postgres-XL/Postgres-XL,zeroae/postgres-xl,jmcatamney/gpdb,adam8157/gpdb,ashwinstar/gpdb,pavanvd/postgres-xl,xinzweb/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,zeroae/postgres-xl,pavanvd/postgres-xl,xinzweb/gpdb,xinzweb/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,adam8157/gpdb,xinzweb/gpdb,lisakowen/gpdb,50wu/gpdb,techdragon/Postgres-XL,adam8157/gpdb,ovr/postgres-xl,pavanvd/postgres-xl,Postgres-XL/Postgres-XL,adam8157/gpdb,zeroae/postgres-xl,ovr/postgres-xl,xinzweb/gpdb,jmcatamney/gpdb,ovr/postgres-xl,greenplum-db/gpdb,ashwinstar/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,lisakowen/gpdb,oberstet/postgres-xl,50wu/gpdb,ashwinstar/gpdb,pavanvd/postgres-xl,xinzweb/gpdb,yazun/postgres-xl,xinzweb/gpdb,adam8157/gpdb,greenplum-db/gpdb