Docs: Add a screenshot

Author: sapegin

docs/Maintenance.md

@@ -86,3 +86,5 @@ Here’s a [good example of a change log](https://github.com/styleguidist/react-
 **Note:** do not commit the `Changelog.md` file, the release tool reads the changelog from the commit message. [Read how it works](https://blog.sapegin.me/all/semantic-release/).
 
 **Note:** you may create a pull request for a changelog. Make sure the actual commit in the `master` branch has a `Changelog:` tag for the release tool to see it.
+
+![Commit message with a changelog](https://user-images.githubusercontent.com/70067/66844661-f6f1e600-ef6e-11e9-9d63-dba607d3c94b.png)