add newsletter to release doc
add newsletter to release doc

Conflicts:
	doc/release/monthly.md

8thcolor/rubyconfau2015-sadr,8thcolor/rubyconfau2015-sadr,8thcolor/eurucamp2014-htdsadr,8thcolor/eurucamp2014-htdsadr,8thcolor/eurucamp2014-htdsadr,8thcolor/rubyconfau2015-sadr