Update release.md

Author: Seth Tisue

.github/ISSUE_TEMPLATE/release.md

@@ -117,3 +117,4 @@ Key links:
 ### Afterwards
 - [ ] Create PR to update `versions.properties` (new file generated by the bootstrap job) and the `baseVersion` in `build.sbt`
 - [ ] Create PR to update https://github.com/lightbend/reactive-platform-docs/blob/master/src/main/paradox/supported-modules/index.md
+- [ ] Update [WhiteSource](https://www.whitesourcesoftware.com)