doc: Spell checking

doc/src/sgml/bgworker.sgml

doc/src/sgml/catalogs.sgml

doc/src/sgml/config.sgml

doc/src/sgml/datatype.sgml

doc/src/sgml/fdwhandler.sgml

doc/src/sgml/func.sgml

doc/src/sgml/high-availability.sgml

doc/src/sgml/indexam.sgml

doc/src/sgml/json.sgml

doc/src/sgml/libpq.sgml

doc/src/sgml/logicaldecoding.sgml

doc/src/sgml/monitoring.sgml

doc/src/sgml/perform.sgml

doc/src/sgml/pgstatstatements.sgml

doc/src/sgml/plpgsql.sgml

doc/src/sgml/protocol.sgml

doc/src/sgml/queries.sgml

doc/src/sgml/recovery-config.sgml

doc/src/sgml/ref/create_aggregate.sgml

doc/src/sgml/ref/create_view.sgml