Add documentation for the library interface

This commit adds documentation for the library interface, formerly
known as tempest-lib, and the release versioning.

Partially implements bp tempest-lib-reintegration

Change-Id: I623222a17fe3563bbe767fa803e8f771a21687a1
diff --git a/doc/source/library/rest_client.rst b/doc/source/library/rest_client.rst
new file mode 100644
index 0000000..3045694
--- /dev/null
+++ b/doc/source/library/rest_client.rst
@@ -0,0 +1,11 @@
+.. _rest_client:
+
+Rest Client Usage
+=================
+
+----------------------
+The rest_client module
+----------------------
+
+.. automodule:: tempest.lib.common.rest_client
+   :members: