Development: edit CONTIRIBUTING rule for requesting pull and for merging
Development: edit CONTIRIBUTING rule for requesting pull and for merging

For maintainers and everyone, some rules were added.
From now, it is needed for requesting commits to be reviewed by at least
two maintainers.

Signed-off-by: drzix <75c00122d1417de46f33afdfc0ba3516a681310e@gmail.com>

drzix/z-Chrome,drzix/z-Chrome