--release doesn't do what I expect

[techtangents]

I'd like to run a command which releases the Unreleased section.

e.g. before:

## [Unreleased]
### Added
- feature1
- feature2

after:

## [Unreleased]

## [1.2.3] - 2021-03-01
### Added
- feature1
- feature2

yarn changelog --release doesn't seem to do this. My changelog gets normalized, but nothing else seems to happen.

[oscarotero]

It's because you don't have the number of the unreleased version. ATM, this library doesn't generate the new version number because it can be a patch, minor or major version. This command was created to generate automatically the release date in this case:

## [1.2.3] - Unreleased
### Added
- feature1
- feature2

Maybe, a way to generate the version number is implementing something like --release=minor, --release=major, etc.

[techtangents]

For my use case, it'd be convenient to pass in the version number. e.g.

--release 1.2.3

or

--release --version 1.2.3

[oscarotero]

Ok, that's easier. I'll do that.

[oscarotero]

Done!
v0.10.4 released. Now you can run --release 1.2.3

[techtangents]

Wow, that was fast. Thank you very much!

Are you able to please add a new # Unreleased header above that?