New guide: How to perform hardforks on a running blockchain

[Tschakki]

Description

A guide about how to perform hardforks on a running blockchain should be added to the documentation.

Motivation

Saying two months into the project and the blockchain's existence I realize that crucial assets are missing and I also need to write an additional module to complete my on-chain usecase. This should then be a hard-fork of my already existing blockchain. Is the SDK offering tools to assist all my validators to update to the new on-chain architecture?

Additional information