Added info about changein versioning scheme

According to kubernetes-client#1244 the information about the change in the versioning scheme should be added one last time in the version 19.0.0. Did that. That way issue 1244 could also be closed.

Author: LevonTostig

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Kubernetes API Version: v1.19.15
 
+**Important Information:**
+
+- The Kubernetes Python client versioning scheme has changed. The version numbers used till Kubernetes Python Client v12.y.z lagged behind the actual Kubernetes minor version numbers. From this release, the client is moving a version format `vY.Z.P` where `Y` and `Z` are respectively from the Kubernetes version `v1.Y.Z` and `P` would incremented due to changes on the Python client side itself. Ref: https://github.com/kubernetes-client/python/issues/1244
+
 ### Bug Fix
 - Type checking in `Client.serialize_body()` was made more restrictive and robust. ([kubernetes-client/python-base#241](https://github.com/kubernetes-client/python-base/pull/241), [@piglei](https://github.com/piglei))