Merge pull request #122 from gyliu513/pr-reviewers

Updated PR template by adding default reviewers.

Author: k8s-ci-robot

.github/PULL_REQUEST_TEMPLATE.md

@@ -11,6 +11,10 @@
 **Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
 Fixes #
 
+** Specify your PR reviewers**:
+<!-- Add or remove reviewers as your request -->
+/cc @gyliu513 @jichenjc @xunpan
+
 **Special notes for your reviewer**:
 
 /sig ibmcloud