Improve the custom_object.py to be more specific to usage of namespaced custom resource

[Priyankasaggu11929]

Link to the issue (please include a link to the specific documentation or example):
https://github.com/kubernetes-client/python/tree/master/examples

Description of the issue (please include outputs or screenshots if possible):

The examples/custom_object.py example script can be improved by making it more specific to usage of kubernetes.client.CustomObjectsApi for a namespaced scope custom resource.

Following are the suggestion for improvement:

• rename the file to namespaced_custom_object.py
• include example usage of patch_namespaced_custom_object method

[Priyankasaggu11929]

cc @Yashks1994

[Yashks1994]

/assign

[Yashks1994]

Opened a PR- #1439