link the psycopg2 fast execution document to the Core tutorial executemany section
link the psycopg2 fast execution document to the Core tutorial executemany section

Fixes: #4109

Change-Id: I62fcb703b552db842be335c8f9257cc0e8c5cdd5

monetate/sqlalchemy,j5int/sqlalchemy,sqlalchemy/sqlalchemy,wujuguang/sqlalchemy,graingert/sqlalchemy,monetate/sqlalchemy,zzzeek/sqlalchemy,graingert/sqlalchemy,wujuguang/sqlalchemy,j5int/sqlalchemy