Update contributing guidelines and the PR template (#9700)

Author: elliette

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,19 +1,46 @@
-*Replace this paragraph with a description of what this PR is changing or adding, and why. Consider including before/after screenshots.*
-
 *List which issues are fixed by this PR.*
 
-*Please add a note to `packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md` if your change requires release notes. Otherwise, add the 'release-notes-not-required' label to the PR.*
+*Replace this paragraph with a description of what this PR is changing or adding, and why. If your PR is updating any UI functionality, please include include before/after screenshots and/or a gif of the UI interaction.*
 
 ## Pre-launch Checklist
 
+### General checklist
+
 - [ ] I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
 - [ ] I read the [Tree Hygiene] wiki page, which explains my responsibilities.
 - [ ] I read the [Flutter Style Guide] _recently_, and have followed its advice.
 - [ ] I signed the [CLA].
-- [ ] I listed at least one issue that this PR fixes in the description above.
 - [ ] I updated/added relevant documentation (doc comments with `///`).
-- [ ] I added new tests to check the change I am making, or there is a reason for not adding tests.
 
+### Issues checklist
+
+- [ ] I listed at least one issue that this PR fixes in the description above.
+- [ ] I listed at least one issue which has the [`contributions-welcome`] or [`good-first-issue`] label. 
+- [ ] I did not list at least one issue with the [`contributions-welcome`] or [`good-first-issue`] label. I understand this means my PR might take longer to be reviewed. 
+
+### Tests checklist
+
+- [ ] I added new tests to check the change I am making...
+- [ ] OR there is a reason for not adding tests, which I explained in the PR description.
+
+### AI-tooling checklist
+
+- [ ] I did not use any AI tooling in creating this PR.
+- [ ] OR I did use AI tooling, and...
+    * [ ] I read the [AI contributions guidelines] and agree to follow them.
+    * [ ] I reviewed all AI-generated code before opening this PR.
+    * [ ] I understand and am able to discuss the code in this PR.
+    * [ ] I have verifed the accuracy of any AI-generated text included in the PR description.
+    * [ ] I commit to verifying the accuracy of any AI-generated code or text that I upload in response to review comments.
+
+### Feature-change checklist 
+
+- [ ] This PR does not change the DevTools UI or behavior and...
+    * [ ] I added the `release-notes-not-required` label or left a comment requesting the label be added.
+- [ ] OR this PR does change the DevTools UI or behavior and...
+    * [ ] I added an entry to `packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md`.
+    * [ ] I included before/after screenshots and/or a GIF demo of the new UI to my PR description.
+    * [ ] I ran the DevTools app locally to manually verify my changes.
 
 ![build.yaml badge]
 
@@ -24,5 +51,8 @@ If you need help, consider asking for help on [Discord].
 [Tree Hygiene]: https://github.com/flutter/flutter/blob/master/docs/contributing/Tree-hygiene.md
 [Flutter Style Guide]: https://github.com/flutter/flutter/blob/master/docs/contributing/Style-guide-for-Flutter-repo.md
 [CLA]: https://cla.developers.google.com/
-[Discord]: https://github.com/flutter/flutter/blob/master/docs/contributing/Chat.md
+[`contributions-welcome`]: https://github.com/flutter/devtools/issues?q=state%3Aopen%20label%3Acontributions-welcome
+[`good-first-issue`]: https://github.com/flutter/devtools/issues?q=state%3Aopen%20label%3Agood-first-issue
+[AI contributions guideline]: https://github.com/flutter/flutter/blob/master/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines
 [build.yaml badge]: https://github.com/flutter/devtools/actions/workflows/build.yaml/badge.svg
+[Discord]: https://github.com/flutter/flutter/blob/master/docs/contributing/Chat.md

CONTRIBUTING.md

@@ -22,6 +22,10 @@ We gladly accept contributions via GitHub pull requests! We encourage you to rea
 framework's contributing guide, as all of that information applies to contributing to the `flutter/devtools`
 repo as well.
 
+We prioritize reviewing PRs that address issues with the following labels:
+* [`good-first-issue`](https://github.com/flutter/devtools/issues?q=state%3Aopen%20label%3Agood-first-issue): Small and easy issues that can be tackled by a first-time contributor.
+* [`contributions-welcome`](https://github.com/flutter/devtools/issues?q=state%3Aopen%20label%3Acontributions-welcome): Issues of any size or difficulty that we consider high-priority fixes.
+
 We communicate primarily over GitHub and [Discord](https://github.com/flutter/flutter/blob/master/docs/contributing/Chat.md) on the
 [#hackers-devtools](https://discord.com/channels/608014603317936148/1106667330093723668) channel.