Update CONTRIBUTE.md

adding release checklist
update yui to 3.11.0
add history entry of yui version update
bumping version 0.5.6
update yui version
Merge pull request #19 from lzhan/updateyui

update yui to 3.11.0
update yui version for example
Merge pull request #20 from lzhan/updateyui

update yui version for example
merging upstream