cargo: prepare release 0.33

[erwanor]

This PR:

• cargo: release ibc-proto-rs@0.33 #123
• docs: create a simple CONTRIBUTING.md #124

[erwanor]

Odd, I just ran unclog build > CHANGELOG.md and staged the changes but it looks like it has removed some dates and reformatted a bunch of other entries. What command do you typically use?

[romac]

I usually run unclog build -u and then copy-paste the section for the new release at the top of the CHANGELOG and add the date manually (+ some reformatting when needed).

[romac]

I've updated the contributing guidelines with more detailed information.

[erwanor]

Thanks, I'll restage the changelog

[Farhad-Shabani]

🙏