Declare a few more interface as stable interface

The below interfacs are meant to be stable interface
for tempest plugins to use but we forgot to update the
document for that.

This commits declare (with release notes as well as doc
update) the below interface as stable interface:

* tempest.common.compute
* tempest.common.identity
* tempest.common.image
* tempest.common.object_storage

Change-Id: Ia67516de51bced215b85eb2a96761ed3ad6c1e51
Signed-off-by: Ghanshyam <gmaan@ghanshyammann.com>
diff --git a/doc/source/plugins/plugin.rst b/doc/source/plugins/plugin.rst
index 31aa134..573aa7d 100644
--- a/doc/source/plugins/plugin.rst
+++ b/doc/source/plugins/plugin.rst
@@ -29,6 +29,10 @@
 * tempest.config
 * tempest.test_discover.plugins
 * tempest.common.credentials_factory
+* tempest.common.compute
+* tempest.common.identity
+* tempest.common.image
+* tempest.common.object_storage
 * tempest.clients
 * tempest.test
 * tempest.scenario.manager
diff --git a/releasenotes/notes/plugin-sytable-interface-18f865ba3a415c70.yaml b/releasenotes/notes/plugin-sytable-interface-18f865ba3a415c70.yaml
new file mode 100644
index 0000000..6d466c7
--- /dev/null
+++ b/releasenotes/notes/plugin-sytable-interface-18f865ba3a415c70.yaml
@@ -0,0 +1,9 @@
+---
+prelude: |
+    Tempest declares the following interface as a stable interface
+    to be used by the tempest plugins:
+
+    * tempest.common.compute
+    * tempest.common.identity
+    * tempest.common.image
+    * tempest.common.object_storage