feat(github): add github issue template configuration

- disallow blank issues
- add discussions contact link for help (relates to #95)

Author: qdm12

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Need help
+    url: https://github.com/ava-labs/libevm/discussions/new/choose
+    about: Please create a Github discussion.