doc(distr): add CP section and Vesting account note

[tbruyelle]

Rendered version

[tbruyelle]

Numbers check out to me when following the guide for generating them 💯 The guides were pretty good, thank you @tbruyelle.

I've also went through parts of the govbox code that relate to distribution, and it also seems alright 👍

I've found a few broken links, but nothing major:

• block 18010657 export link not working atomone.fra1.digitaloceanspaces.com/cosmoshub4/cosmoshub-4-export-18010657.json
• block 18010658 export link not working atomone.fra1.digitaloceanspaces.com/cosmoshub4/cosmoshub-4-export-18010658.json

Thank you for the fast verification @zivkovicmilos ! For the audience, the broken links are in the govbox documentation, they are fixed now, it was a typo in the bucket directory. Thanks for pointing them!