Add conventional changelog tool + documentation

[sinedied]

Base on this article idea (point 6), I think that support for conventional changelog would be a nice addition and should be proposed as an option or add-on (to be discussed).

Any feedback and propositions welcome here 😃

It's already used in angular and other popular projects, and is a great way in my opinion to maintain changelog for apps. Here is the commit "spec": https://conventionalcommits.org

Tasks:

• [ ] add doc to explain the basics of conventional commits and syntax (+ references)
• [ ] add a release script that call standard-version to generate changelog, bump version, create a git tag and eventually push it

[Fairen]

To ensure the commit messages are corectly formated for conventional changelog generation, theses tools could be intersting :

• conventional-changelog-cli
• commitizen and git-cz

What do you think ?

[sinedied]

Yes, you can take also some inspiration in the config used for publishing this package itself. Though the final public is done with semantic-release which may not be applicable to publish an angular app, that's why I suggested standard-version.