shorter PR template (#63481)

It takes up precious seconds of my time on this planet to delete all of
the boilerplate text here.

Author: sqs

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,41 +1,9 @@
-<!-- 💡 To write a useful PR description, make sure that your description covers:
-- WHAT this PR is changing:
-    - How was it PREVIOUSLY.
-    - How it will be from NOW on.
-- WHY this PR is needed.
-- CONTEXT, i.e. to which initiative, project or RFC it belongs.
-
-The structure of the description doesn't matter as much as covering these points, so use
-your best judgement based on your context.
-Learn how to write good pull request description: https://www.notion.so/sourcegraph/Write-a-good-pull-request-description-610a7fd3e613496eb76f450db5a49b6e?pvs=4 -->
-
+<!-- PR description tips: https://www.notion.so/sourcegraph/Write-a-good-pull-request-description-610a7fd3e613496eb76f450db5a49b6e -->
 
 ## Test plan
 
-<!-- All pull requests REQUIRE a test plan: https://docs-legacy.sourcegraph.com/dev/background-information/testing_principles -->
-
-
-## Changelog
-
-<!--
-1. Ensure your pull request title is formatted as: $type($domain): $what
-2. Add bullet list items for each additional detail you want to cover (see example below)
-3. You can edit this after the pull request was merged, as long as release shipping it hasn't been promoted to the public.
-4. For more information, please see this how-to https://www.notion.so/sourcegraph/Writing-a-changelog-entry-dd997f411d524caabf0d8d38a24a878c?
-
-Audience: TS/CSE > Customers > Teammates (in that order).
-
-Cheat sheet: $type = chore|fix|feat $domain: source|search|ci|release|plg|cody|local|...
--->
-
-<!--
-Example:
-
-Title: fix(search): parse quotes with the appropriate context
-Changelog section:
+<!-- REQUIRED; info at https://docs-legacy.sourcegraph.com/dev/background-information/testing_principles -->
 
 ## Changelog
 
-- When a quote is used with regexp pattern type, then ...
-- Refactored underlying code.
--->
+<!-- OPTIONAL; info at https://www.notion.so/sourcegraph/Writing-a-changelog-entry-dd997f411d524caabf0d8d38a24a878c -->