Tests for Nova instance diagnostics (microversion v2.48)

Existing instance diagnostics tests were moved to the new files
to test diagnostics for different microversions (2.1 and 2.48).

Depends-On: If0b1493cc5c1c7f0d9896dd68342ad4dea4f7da2

Change-Id: I7757c5beeea3d3b0bc15a51cafc5ea2ada65e76c
diff --git a/doc/source/microversion_testing.rst b/doc/source/microversion_testing.rst
index 9690923..d6d90ba 100644
--- a/doc/source/microversion_testing.rst
+++ b/doc/source/microversion_testing.rst
@@ -330,6 +330,10 @@
 
  .. _2.47: http://docs.openstack.org/developer/nova/api_microversion_history.html#id42
 
+ * `2.48`_
+
+ .. _2.48: http://docs.openstack.org/developer/nova/api_microversion_history.html#id43
+
 * Volume
 
  * `3.3`_