Add REST docs stub for Copilot pull request review API

Adds content/rest/pulls/copilot-review.md (auto-generated content will be
filled in once github/rest-api-description picks up the new operations
from github/github) and links from the existing review-requests page.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: obvioussean

content/rest/pulls/copilot-review.md

@@ -0,0 +1,22 @@
+---
+title: REST API endpoints for the Copilot code review on a pull request
+shortTitle: Copilot review
+allowTitleToDifferFromFilename: true
+intro: 'Use the REST API to request a {% data variables.copilot.copilot_code-review_short %} on a pull request and to manage per-PR review preferences.'
+versions: # DO NOT MANUALLY EDIT. CHANGES WILL BE OVERWRITTEN BY A 🤖
+  fpt: '*'
+  ghec: '*'
+autogenerated: rest
+category:
+  - Manage issues, pull requests, and projects
+---
+
+## About requesting a {% data variables.copilot.copilot_code-review_short %}
+
+You can use the REST API to ask {% data variables.product.prodname_copilot_short %} to review a pull request, optionally telling it how much effort to spend on the review and whether to re-review the pull request automatically on every new push.
+
+This endpoint is preferred over adding the `copilot-pull-request-reviewer[bot]` user as a reviewer through the `requested_reviewers` endpoint. Both flows produce the same Copilot review under the hood, but the dedicated endpoint accepts per-PR preferences and returns a structured response.
+
+These endpoints are only available on {% data variables.product.prodname_dotcom_the_website %} and {% data variables.product.prodname_ghe_cloud %}. They return `404` on {% data variables.product.prodname_ghe_server %}.
+
+<!-- Content after this section is automatically generated -->

content/rest/pulls/review-requests.md

@@ -16,4 +16,6 @@ category:
 
 Pull request authors and repository owners and collaborators can request a pull request review from anyone with write access to the repository. Each requested reviewer will receive a notification asking them to review the pull request.
 
+To request a review specifically from {% data variables.product.prodname_copilot_short %} — and to set per-PR preferences such as the review effort level or whether to re-review on each new push — use the dedicated [Copilot review endpoints](/rest/pulls/copilot-review) instead of adding the Copilot bot to this endpoint.
+
 <!-- Content after this section is automatically generated -->