infrastructure: add issue templates

.github/ISSUE_TEMPLATE/bug.md

@@ -0,0 +1,23 @@
+---
+name: Bug report
+labels: [bug, needs-triage]
+about: Create a report to help us improve
+---
+
+<!--
+Please do not use the issue queue for questions or troubleshooting. Unless you are certain that your issue is a software defect, use the discussion forum of our repo:
+
+https://github.com/google/docsy/discussions
+-->
+
+<!-- Please answer these questions before submitting your issue. Thanks! -->
+
+### What version of Docsy are you using?
+
+### How did you install Docsy (hugo module, npm or git submodule)?
+
+### What version of Hugo are you using (`hugo version`)?
+
+<pre>
+$ hugo version
+</pre>

.github/ISSUE_TEMPLATE/config.yml

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+blank_issues_enabled: false
+contact_links:
+  - name: SUPPORT, ISSUES, and TROUBLESHOOTING
+    url: https://github.com/google/docsy/discussions
+    about:
+      Please DO NOT use GitHub issues for support requests, instead start a
+      discussion thread at https://github.com/google/docsy/discussions.
+      Feel free to open an issue once your problem is confirmed by the docsy
+      maintainers and/or the docsy community.

.github/ISSUE_TEMPLATE/enhancement.md

@@ -0,0 +1,6 @@
+---
+name: Enhancement proposal
+labels: [enhancement, needs-triage]
+---
+
+<!-- Describe this new feature. Think about if it really belongs in the docsy theme; you may want to discuss it on https://github.com/google/docsy/discussions first.  -->