Update readme and contributing files

.github/CONTRIBUTING.md

@@ -1,3 +1,5 @@
-Ask questions at [StackOverflow](https://stackoverflow.com/questions/ask?tags=go+redis).
+Ask questions at
+[StackOverflow](https://stackoverflow.com/questions/ask?tags=go+redis).
 
-Send email to Gary Burd (address in GitHub profile) before doing any work on Redigo.
+[Open an issue](https://github.com/garyburd/redigo/issues/new) to discuss your
+plans before doing any work on Redigo.

README.markdown

@@ -42,7 +42,7 @@ Related Projects
 Contributing
 ------------
 
-Send email to Gary Burd (address in GitHub profile) before doing any work on Redigo.
+See [CONTRIBUTING.md](https://github.com/garyburd/redigo/blob/master/.github/CONTRIBUTING.md).
 
 License
 -------