Add changelog

[Jack Morgan]

I use yattag as a dependency for a project, and are notified by pyup when a new version of this module is available. However without a changelog, I cannot easily see what is changed. Our testing system checks it doesn't break anything outright, but it would be great to have a list of changes, plus tagged releases on GitHub (so we can easily see a git diff of changes) to know if there is anything we should be aware of when updating.

I found this website really useful in helping us to create a changelog.

Thanks for a very useful package!

[Benjamin Le Forestier]

Thanks for the suggestion. I'll look into this next time I make a change. I'll definitely tag releases.