docs: clarify changelog-types and its implications to version bumps (…

…#844)

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Relating to [release-please
issue](googleapis/release-please#2096)

I was surprised that adding different changelog types result in patch
version bumps. I wasn't expecting this but going through the code it
seemed to be expected but undocumented behavior.

And this is why I would like to document the behavior here so other
people know and can plan whether to use it or not.

cheers!

---------

Signed-off-by: Tommi Tampio <46082658+stutommi@users.noreply.github.com>
Co-authored-by: Jeff Ching <chingor@google.com>

README.md

@@ -59,7 +59,7 @@ Automate releases with Conventional Commit Messages.
 |  `bump-patch-for-minor-pre-major`  | Should feat changes before 1.0.0 produce patch bumps instead of minor bumps?  Default `false`                                                                                                                                                                                                                                                                 |
 |               `path`               | create a release from a path other than the repository's root                                                                                                                                                                                                                                                                                                 |
 |          `monorepo-tags`           | add prefix to tags and branches, allowing multiple libraries to be released from the same repository.                                                                                                                                                                                                                                                         |
-|         `changelog-types`          | A JSON formatted String containing to override the outputted changelog sections                                                                                                                                                                                                                                                                               |
+|         `changelog-types`          | A JSON formatted String containing to override the outputted changelog sections. Defined types may trigger version bumps.                                                                                                                                                                                                                                                                                |
 |           `version-file`           | provide a path to a version file to increment (used by ruby releaser)                                                                                                                                                                                                                                                                                         |
 |           `extra-files`            | add extra-files to bump using the [generic updater](https://github.com/googleapis/release-please/blob/main/docs/customizing.md#updating-arbitrary-files)                                                                                                                                                                                                      |
 |               `fork`               | Should the PR be created from a fork. Default `false`                                                                                                                                                                                                                                                                                                         |