Adjust GitHub issues URL to include PRs + closed

Hopefully this helps users find PRs and closed issues more easily when they're going to file an issue.

.template-helpers/issues.md

@@ -1 +1 @@
-[%%GITHUB-REPO%%/issues](%%GITHUB-REPO%%/issues)
+[%%GITHUB-REPO%%/issues](%%GITHUB-REPO%%/issues?q=)