add files to bump commit

## 🚀 Feature Proposal

Right now this tool bump a new version and push the package.json in the repo:

https://github.com/fastify/releasify/blob/822d224d1beff58d4454866f8eb0e6fb9b20352a/lib/commands/publish.js#L129

If a user (like me 😇) have a `prepublish` or `postpublish` script that updates some files like the README.md will have a mismatch between the published version and the repository version (unless the user will commit the additional files to master by himself)

So it would be good to add a flag to let the user:
- define a list of files to add to the bump commit
- or simply run `git add -A` (since the publish command to check if the local repo is aligned with the remote branch).
- or add a flag that will run `git add -A`

WDYT?