Fix docs from I0dc80bee3ba6ff4ec8cc3fc113b6de7807e0bf2a

The CLI usage docs should mention the microversion
restriction for creating a flavor with a description
and setting a description on a flavor. Also, the release
note talks about setting the server description on the
flavor commands (wrong resource).

Change-Id: I93af3da9a0be62395a1c719fd1dcbfd2b669580d
Story: 2002196
Task:  22607

Author: mriedem

doc/source/cli/command-objects/flavor.rst

@@ -79,7 +79,8 @@ Create new flavor
 
 .. option:: --description <description>
 
-    Description to add for this flavor
+    Description to add for this flavor. Only available starting with
+    ``--os-compute-api-version 2.55``.
 
 .. _flavor_create-flavor-name:
 .. describe:: <flavor-name>
@@ -176,7 +177,8 @@ Set flavor properties
 
 .. option:: --description <description>
 
-    Set description to this flavor
+    Description to set for this flavor. Only available starting with
+    ``--os-compute-api-version 2.55``.
 
 .. describe:: <flavor>
 

releasenotes/notes/flavor-add-description-b618abd4a7fb6545.yaml

@@ -1,6 +1,8 @@
 ---
 features:
   - Add ``--description`` option to ``flavor set`` command to update the
-    description of the server.
+    description of the flavor. Only available starting with
+    ``--os-compute-api-version 2.55``.
   - Add ``--description`` option to ``flavor create`` command to set the
-    description of the server.
+    description of the flavor. Only available starting with
+    ``--os-compute-api-version 2.55``.