doc: mention adding YAML for APIs in PR contributing guide

PR-URL: #35459
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Mary Marchini <oss@mmarchini.me>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

doc/guides/contributing/pull-requests.md

@@ -130,7 +130,17 @@ Any documentation you write (including code comments and API documentation)
 should follow the [Style Guide](../doc-style-guide.md). Code samples
 included in the API docs will also be checked when running `make lint` (or
 `vcbuild.bat lint` on Windows). If you are adding to or deprecating an API,
-use `REPLACEME` for the version number in the documentation YAML.
+add or change the appropriate YAML documentation. Use `REPLACEME` for the
+version number in the documentation YAML:
+
+```markdown
+### `request.method`
+<!-- YAML
+added: REPLACEME
+-->
+
+* {string} The request method.
+```
 
 For contributing C++ code, you may want to look at the
 [C++ Style Guide](../cpp-style-guide.md), as well as the