Add note about release notes to CONTRIBUTING.md

Author: wvu

CONTRIBUTING.md

@@ -46,6 +46,7 @@ and Metasploit's [Common Coding Mistakes].
 * **Do** include [console output], especially for witnessable effects in `msfconsole`.
 * **Do** list [verification steps] so your code is testable.
 * **Do** [reference associated issues] in your pull request description
+* **Do** write [release notes] once a pull request is landed
 * **Don't** leave your pull request description blank.
 * **Don't** abandon your pull request. Being responsive helps us land your code faster.
 
@@ -108,6 +109,7 @@ already way ahead of the curve, so keep it up!
 [console output]:https://help.github.com/articles/github-flavored-markdown#fenced-code-blocks
 [verification steps]:https://help.github.com/articles/writing-on-github#task-lists
 [reference associated issues]:https://github.com/blog/1506-closing-issues-via-pull-requests
+[release notes]:https://github.com/rapid7/metasploit-framework/wiki/Adding-Release-Notes-to-PRs
 [PR#2940]:https://github.com/rapid7/metasploit-framework/pull/2940
 [PR#3043]:https://github.com/rapid7/metasploit-framework/pull/3043
 [pre-commit hook]:https://github.com/rapid7/metasploit-framework/blob/master/tools/dev/pre-commit-hook.rb