add CII Best Practices badge to README
add CII Best Practices badge to README

Signed-off-by: Jared Watts <d81dfc8bbf0a29009cd655fe5ce0d82500efb58c@gmail.com>

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