CONTRIBUTING/README update
@adam-mercer : Some quick updates to the contributing guide and package-level README.
- Redirected CW links.
- The service desk e-mail was only listed at package level, not in the main CONTRIBUTING.md
- There's actually a new address for that which should work with more providers (apparently the '/' in the old one caused probolems); thanks to @thomas.downes for pointing this out. Also updated at the package-level.
(I have no idea what "1438" means in the address... probably just an internal project counter.)