docs: update pull request template (@fehmer) (monkeytypegame#6538)

Author: fehmer

.github/pull_request_template.md

@@ -6,10 +6,22 @@
 
 - [ ] Adding quotes?
   - [ ] Make sure to include translations for the quotes in the description (or another comment) so we can verify their content.
-- [ ] Adding a language or a theme?
-  - [ ] If is a language, did you edit `_list.json`, `_groups.json` and add `languages.json`?
-  - [ ] If is a theme, did you add the theme.css?
-    - Also please add a screenshot of the theme, it would be extra awesome if you do so!
+- [ ] Adding a language?
+  - Make sure to follow the [languages documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/LANGUAGES.md)
+  - [ ] Add language to `packages/contracts/src/schemas/languages.ts`
+  - [ ] Add language to exactly one group in `frontend/src/ts/constants/languages.ts`
+  - [ ] Add language json file to `frontend/static/languages` 
+- [ ] Adding a theme?
+  - Make sure to follow the [themes documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/THEMES.md)
+  - [ ] Add theme to `packages/contracts/src/schemas/themes.ts`
+  - [ ] Add theme to `frontend/src/ts/constants/themes.ts`
+  - [ ] Add theme css file to `frontend/static/themes` 
+- [ ] Adding a layout?
+  - [ ] Make sure to follow the [layouts documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/LAYOUTS.md)
+  - [ ] Add layout to `packages/contracts/src/schemas/layouts.ts`
+  - [ ] Add layout json file to `frontend/static/layouts` 
+  - Also please add a screenshot of the theme, it would be extra awesome if you do so!
+  
 - [ ] Check if any open issues are related to this PR; if so, be sure to tag them below.
 - [ ] Make sure the PR title follows the Conventional Commits standard. (https://www.conventionalcommits.org for more info)
 - [ ] Make sure to include your GitHub username prefixed with @ inside parentheses at the end of the PR title.