Add link to the reviewers

.github/PULL_REQUEST_TEMPLATE.md

@@ -1 +1 @@
-Thanks for contributing to TVM!   Please refer to guideline https://docs.tvm.ai/contribute/ for useful information and tips. After the pull request is submitted, please request code reviews from others in the community.
+Thanks for contributing to TVM!   Please refer to guideline https://docs.tvm.ai/contribute/ for useful information and tips. After the pull request is submitted, please request code reviews from [Reviewers](https://github.com/dmlc/tvm/blob/master/CONTRIBUTORS.md#reviewers).