meta: Add Showcase section to PR template

.github/linters/.markdown-lint.yml

@@ -1,3 +1,9 @@
 {
-    "MD013": false
+    "MD013": false,
+    "no-inline-html": {
+        "allowed_elements": [
+            "details",
+            "summary"
+        ]
+    }
 }

.github/pull_request_template.md

@@ -16,14 +16,26 @@
 
 ---
 
-## Changelog
+## Showcase
 
-> This section is optional. If this was a trivial fix, or has no externally-visible impact, you can delete this section.
+> This section is optional. If this PR does not include a visual change or does not add a new feature, you can delete this section.
 
-- What changed as a result of this PR?
-- If applicable, organize changes under "Added", "Changed", or "Fixed" sub-headings
-- Stick to one or two sentences. If more detail is needed for a particular change, consider adding it to the "Solution" section
-  - If you can't summarize the work, your change may be unreasonably large / unrelated. Consider splitting your PR to make it easier to review and merge!
+- Help others understand the result of this PR by showcasing your awesome work!
+- If this PR adds a new feature or public API, consider adding a brief pseudo-code snippet of it in action
+- If this PR includes a visual change, consider adding a screenshot, GIF, or video
+  - If you want, you could even include a before/after comparison!
+- If the Migration Guide adequately covers the changes, you can delete this section
+
+While a showcase should aim to be brief and digestible, you can use a toggleable section to save space on longer showcases:
+
+<details>
+  <summary>Click to view showcase</summary>
+
+```rust
+println!("My super cool code.");
+```
+
+</details>
 
 ## Migration Guide