doc: improve schema docs
doc: improve schema docs

nbushak/postgraphql,calebmer/postgraphql,ferdinandsalis/postgraphql,calebmer/postgraphql,postgraphql/postgraphql,nbushak/postgraphql,calebmer/postgraphql,nbushak/postgraphql,calebmer/postgraphql,ferdinandsalis/postgraphql,postgraphql/postgraphql,postgraphql/postgraphql,nbushak/postgraphql,postgraphql/postgraphql