Support Adding Additional Changelog Types

### TL;DR

I need to generate a changelog without PR links for each commit and would like to do so by adding my own `changelog-type` as described [here](https://github.com/googleapis/release-please/blob/main/docs/customizing.md#adding-additional-changelog-types).

### Detailed design

Docs mentioned that we can use [ChangelogNotes interface](https://github.com/googleapis/release-please/blob/main/src/changelog-notes.ts) to add [additional changelog types](https://github.com/googleapis/release-please/blob/main/docs/customizing.md#adding-additional-changelog-types); but this seems to not apply to the Github action.

### Additional information

_No response_