Update docs/RELEASE_ISSUE_TEMPLATE.md

docs/RELEASE_ISSUE_TEMPLATE.md

@@ -22,7 +22,7 @@ For each RC published in each stage:
 
 - version string in `version.go` has been updated
 - tag commit with vX.Y.Z-rcN
-- [ ] Stage 1 - Internal Testing
+- [ ] **Stage 1 - Internal Testing**
   - [ ] Feature freeze. If any non-trivial features get added to the release, uncheck all the checkboxes and return to this stage.
   - [ ] CHANGELOG.md has been updated
     - use `./bin/mkreleaselog` to generate a nice starter list