pr: add more items to the checklist
pr: add more items to the checklist

* when submitting code people must be provide unit tests
* when submitting code for a new functionnality, integration tests must
be added so we can get coverage of that feature in the CI.

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

rook/rook,rook/nfs,rook/rook,rook/rook,rook/rook,rook/nfs,rook/rook,rook/nfs