doc: suggest nodejs/help for general support

This commit adds a reference to `nodejs/help` in the github template.

PR-URL: https://github.com/nodejs/node/pull/9128
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

.github/ISSUE_TEMPLATE.md

@@ -1,5 +1,11 @@
 <!--
 Thank you for reporting an issue.
+
+This issue tracker is for bugs and issues found within Node.js core.
+If you require more general support please file an issue on our help
+repo. https://github.com/nodejs/help
+
+
 Please fill in as much of the template below as you're able.
 
 Version: output of `node -v`