github: add link to issue template list warning against LLMs

GitHub have introduced an absolutely baffling feature where users can
use Copilot to take their simple explanation of a bug, and reword it
into a multi-paragraph monologue with no interesting details and added
false information, while also potentially ignoring issue templates.

So far, GitHub has not provided a way to block this feature at the
repository or organisation level, so for now, this is the only way to
prevent users from filing LLM-generated slop.

Related: https://github.com/orgs/community/discussions/159749

Author: mlugg

.github/ISSUE_TEMPLATE/config.yml

@@ -5,3 +5,6 @@ contact_links:
   - name: Question
     about: Please use one of the community spaces for questions or general discussions.
     url: https://github.com/ziglang/zig/wiki/Community
+  - name: Copilot and Other LLMs
+    about: Please do not use GitHub Copilot or any other LLM to write an issue.
+    url: https://github.com/ziglang/zig/wiki/Writing-Issues-with-Copilot-and-Other-LLMs