Add compute response schema for microversion 2.75

Compute microversion 2.75 made the rebuild and update server
response same as get servers
- https://docs.openstack.org/nova/latest/reference/api-microversion-history.html#id68

Partially Implements: blueprint fix-microversion-gap

Change-Id: I1728e5de0e815def0fe31c242203bd9f36dc41f4
diff --git a/doc/source/microversion_testing.rst b/doc/source/microversion_testing.rst
index c9db836..5557aa3 100644
--- a/doc/source/microversion_testing.rst
+++ b/doc/source/microversion_testing.rst
@@ -442,6 +442,10 @@
 
   .. _2.73: https://docs.openstack.org/nova/latest/reference/api-microversion-history.html#id66
 
+  * `2.75`_
+
+  .. _2.75: https://docs.openstack.org/nova/latest/reference/api-microversion-history.html#id68
+
   * `2.79`_
 
   .. _2.79: https://docs.openstack.org/nova/latest/reference/api-microversion-history.html#maximum-in-train