[SPARK-6889] [DOCS] CONTRIBUTING.md updates to accompany contribution doc updates#5623

Closed

srowen wants to merge 1 commit intoapache:masterfrom srowen:SPARK-6889

+13-9

Commits on Apr 22, 2015

Part of the SPARK-6889 doc updates, to accompany wiki updates at https://cwiki.apache.org/confluence/display/SPARK/Contributing+to+Spark
srowen
committed