doc(readme): add note on breaking changes
doc(readme): add note on breaking changes

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