corrected links in contribution guide

Author: jakewmeyer

CONTRIBUTING.md

@@ -8,6 +8,6 @@
 Changes will not be merged unless the build passes.
 
 4. If the build succeeds, the pull request will be merged, and automatically
-pushed to the staging server at [http://api.spacexdev.com](http://api.spacexdev.com) for a
-final check before promoting changes to production at [https://api.spacexdata.com](https://api.spacexdata.com).
+pushed to the staging server at [http://stage.spacexdata.com/v1/](http://stage.spacexdata.com/v1/) for a
+final check before promoting changes to production at [https://api.spacexdata.com/v1/](https://api.spacexdata.com/v1/).