Update docs to relfect the changes to QueryBuilder::from made in #646
Merge pull request #647 from JeroenDeDauw/docs

Update docs to relfect the changes to QueryBuilder::from made in #646
Update docs to include warning when using object type with PostgreSQL
Merge pull request #653 from exi/documentation-fix-postgresql-object-type

Update docs to include warning when using object type with PostgreSQL