Prompt users to use Discussions for feature requests (#23821)

I'm moving forward on this - we can revert if it ends up being a bad
move.

Release Notes:

- N/A

.github/ISSUE_TEMPLATE/config.yml

@@ -1,6 +1,9 @@
 # yaml-language-server: $schema=https://json.schemastore.org/github-issue-config.json
 blank_issues_enabled: false
 contact_links:
+  - name: Feature Request
+    url: https://github.com/zed-industries/zed/discussions/new/choose
+    about: To request a feature, open a new Discussion in one of the appropriate Discussion categories
   - name: Zed Discussion Forum
     url: https://github.com/zed-industries/zed/discussions
     about: A community discussion forum