Enable ChangeLog plugin to monitor metric value change

[pilot7777]

ChangeLog plugin is very helpful to monitor state change in volume/node/svm. If it can monitor metric value change, it will be even more useful, such as monitor volume size change via auto grow/shrink.

Thanks!

[rahulguptajss]

@pilot7777 Metrics monitoring using the changelog plugin is available in the nightly build. For more information, Please refer to the updated documentation for the changelog plugin. Please provide your feedback. Thanks.