node: refine TC percentage rules - CONTRIBUTING.md

Clarifies a more definite two-thirds Quorum.
Formally allows 2 out of 6 members of the TC to be associated with a
single employer.

PR-URL: https://github.com/node-forward/node/pull/14
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

CONTRIBUTING.md

@@ -209,8 +209,8 @@ governance rules are:
 
 * [Consensus Seeking](http://en.wikipedia.org/wiki/Consensus-seeking_decision-making)
 * Motions with voting when consensus cannot be reached.
-* Quorum of 60%, simple majority wins.
-* No more than 30% of the TC membership can be affiliated with the same
+* Quorum of 2/3 (66%), simple definite majority wins.
+* No more than 1/3 (34%) of the TC membership can be affiliated with the same
 employer.
 
 ## TC Meetings