improved docs

website/docs/configuration/git.md

@@ -130,6 +130,8 @@ Custom OS commands can also be used for modifying the commit messages:
 
 - `{ pattern = "foo", replace_command = "pandoc -t commonmark"}`
 
+> The above is equivalent to: `echo <macthed_part_of_the_changelog> | pandoc -t commonmark`
+
 This is useful when you want to filter/encode messages using external commands. In the example above, [pandoc](https://pandoc.org/) is used to convert each commit message that matches the given `pattern` to the [CommonMark](https://commonmark.org/) format.
 
 A more fun example would be reversing each commit message: