Add a changelog

[jsanders]

I was just notified that version 1.5.2 has been released and I'm finding it difficult to evaluate whether or not to make it a priority to upgrade the version I'm using, because there is a lot of changed code and many commits to evaluate. A changelog summarizing the major changes in new versions and what they mean to users would be very nice to have.

I'm willing to work on putting it together, but I'm sure I'll need to bug somebody with lots of questions.

Thanks for the great library!

[excpt]

Changelog: https://github.com/jwt/ruby-jwt/releases/tag/jwt-1.5.2

Thanks for the hint.

[jsanders]

@excpt: Ah! Totally missed that, thanks for the link.

[excpt]

Just fixed that. ;) 🍻

[jsanders]

Ah, cheers.