message: Update pull request template link to point to new developer doc location
  Closes:
diff: @@ -18,4 +18,4 @@ The project is undergoing daily changes. Pull Requests will be reviewed and resp
  ## Related PRs
  -(If this PR adds or changes functionality, please take some time to update the docs at https://github.com/libra/website, and link to your PR here.)
  +(If this PR adds or changes functionality, please take some time to update the docs at https://github.com/libra/libra/developers.libra.org, and link to your PR here.)
  