Update NEWS handling section of README.GIT-RULES

See http://marc.info/?t=138124004400005&r=1&w=2
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  Update NEWS handling section of README.GIT-RULES
Merge branch 'PHP-5.5' into PHP-5.6

* PHP-5.5:
  Update NEWS handling section of README.GIT-RULES