Fix typo

Incorrect use of "awhile" on line 466. Should be "a while"
http://grammarist.com/spelling/awhile-a-while/

Author: JoeyPriceless

_articles/how-to-contribute.md

@@ -463,7 +463,7 @@ You should usually open an issue in the following situations:
 Tips for communicating on issues:
 
 * **If you see an open issue that you want to tackle,** comment on the issue to let people know you're on it. That way, people are less likely to duplicate your work.
-* **If an issue was opened awhile ago,** it's possible that it's being addressed somewhere else, or has already been resolved, so comment to ask for confirmation before starting work.
+* **If an issue was opened a while ago,** it's possible that it's being addressed somewhere else, or has already been resolved, so comment to ask for confirmation before starting work.
 * **If you opened an issue, but figured out the answer later on your own,** comment on the issue to let people know, then close the issue. Even documenting that outcome is a contribution to the project.
 
 ### Opening a pull request