Revision message

Problem/Motivation

Read the config revisions better.

Steps to reproduce

1. Enable the configuration revision module and configure it for a config, e.g. Webform.
2. Make changes to the form's configuration in a web form.
3. Navigate to the revision tab of the web form.
4. This shows a static revision message saying "A new revision is saved for Webform Name"

Proposed resolution

Similar to the entity revision message, having a config revision message option would be great.

Remaining tasks

TBD

User interface changes

A plain text field is to be added, to enter the config revision message.

API changes

N/A

Data model changes

TDB