PR template: ask for code examples, and something reviewers can try

.github/pull_request_template.md

@@ -16,6 +16,34 @@ Write "No visible change" if there is none.
 | --- | --- |
 |  |  |
 
+## Code examples
+
+<!--
+Required for any change to how Explore is used or what it writes: a CLI command or flag,
+config.yaml, a workflow template, a file format (a replay or flows file, report JSON), or a
+public type. Show it in use as a reader would write it: the command with its flags, the config
+or file it reads, and what it prints or writes, trimmed to the lines that matter. When existing
+usage changes, show it before and after.
+Write "No change to usage" if there is none.
+-->
+
+```sh
+
+```
+
+## Try it
+
+<!--
+Optional, but recommended: something a reviewer can open or run to see the change for themselves.
+- A Viewer change: the Viewer preview comment on this PR links a live build. Name the report,
+  screen and steps to look at.
+- A capture or report change: a hosted report from a run of this branch (explore:binary,
+  explore:session or capture with --upload), or an app pull request whose review ran this branch.
+- Otherwise: the commands that run it from a checkout of this branch, for example
+  `npm ci && npm run build`, then `node dist/cli.js <command>`, with any app or file it needs.
+Write "Nothing to try" if there is nothing a reviewer could run.
+-->
+
 ## Testing
 
 <!-- What you ran and what you checked by hand. -->