docs(git): improve docs for commit_preprocessors and commit_parsers (#928)

website/docs/configuration/git.md

@@ -103,6 +103,10 @@ a commit being treated as a changelog entry.
 
 An array of commit preprocessors for manipulating the commit messages before parsing/grouping them. These regex-based preprocessors can be used for removing or selecting certain parts of the commit message/body to be used in the following processes.
 
+:::note 
+The `replace` or `replace_command` will take into account of the entire log of commit messages where the specified `pattern` is matched.
+:::
+
 Examples:
 
 - `{ pattern = "foo", replace = "bar"}`
@@ -126,6 +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 "<matched_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:
@@ -138,7 +144,7 @@ A more fun example would be reversing each commit message:
 
 ### commit_parsers
 
-An array of commit parsers for determining the commit groups by using regex.
+An array of commit parsers for determining the commit groups by using regex. The entire commit messages are affected wherever the regex is matched.
 
 Examples: