Add releasenote for add project_id for arq patch api

This is follow up https://review.opendev.org/#/c/738427/6/cyborg/api/rest_api_version_history.rst@18,
and add releasenote for adding `project_id` field to accelerator request
PATCH api.

Change-Id: I4df6a7e91c0a2a06fbf260c6c6790d6160345acd

cyborg/api/rest_api_version_history.rst

@@ -6,6 +6,15 @@ microversion change. The description for each version should be a
 verbose one which has enough information to be suitable for use in
 user documentation.
 
+A user can specify a header in the API request::
+
+  OpenStack-API-Version: accelerator <microversion>
+
+where ``<microversion>`` is any valid api microversion for this API.
+
+If no version is specified then the API will behave as if a version
+request of v2.0 was requested.
+
 2.0
 ---
 
@@ -15,13 +24,6 @@ microversions.
 2.1
 ---
 
-Add ``project_id`` for arq.
+Add ``project_id`` for Accelerator Requests PATCH API. ``project_id`` is
+used to control the operation of arq with different roles.
 
-A user can specify a header in the API request::
-
-  OpenStack-API-Version: accelerator <microversion>
-
-where ``<microversion>`` is any valid api microversion for this API.
-
-If no version is specified then the API will behave as if a version
-request of v2.0 was requested.

releasenotes/notes/add-project_id-to-arq-patch-api-8270cbb26c68af46.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    Add ``project_id`` for Accelerator Requests (arq) `PATCH API`_ from
+    microversion 2.1 in order to control operations of accelerator requests
+    with different roles.
+
+    .. _`PATCH API`: https://docs.openstack.org/api-ref/accelerator/v2/index.html#update-accelerator-requests