update CONTRIBUTING.md
Add multi-record support to attributes_table_for
update 4-csv-format.md
fix typo in docs
Merge pull request #2544 from zorab47/multi-record-attributes-table-for

Add multi-record support to attributes_table_for
Merge branch 'master' of github.com:zorab47/active_admin into add-transposed-table-for-component