docs: Improve feature process (#51425)

Small tweaks to our feature doc and a link out to more about how the
Feature Request process works.

Release Notes:

- N/A

.github/DISCUSSION_TEMPLATE/feature-requests.yml

@@ -40,4 +40,4 @@ body:
     attributes:
       value: |
         Learn more about how feature requests work in our
-        [Feature Request Guidelines](https://github.com/zed-industries/zed/discussions/47963).
+        [Feature Request Guidelines](https://github.com/zed-industries/zed/discussions/51422).