Begin adding Gov2 info to Learn Governance doc

[alfarok]

Description

This PR addresses #3476.

For a first draft I tried to keep most the governance v1 information in-place and add notes on v2 changes and differences where relevant. This ultimately may lead to too much jumping back and forth between the two. If we determine this is the case, I think we can make v1 it's own learn-governance-v1 page and use the learn-governance page to track the latest version (pointing to v1 where necessary). This strategy may be a good option because it won't break any existing links and still preserves the history. It also shouldn't be too much effort to move everything around but I will wait for initial feedback before proceeding.

Main Gov2 source: https://medium.com/polkadot-network/gov2-polkadots-next-generation-of-decentralised-governance-4d9ef657d11b

• [x] Run npx pretty-quick after the review is completed to prevent the code diff from being too overwhelming

[alfarok]

@DrW3RK, with the exception of one outstanding comment above, I think I am ready to pass this one over to you for the next round. Thank you for all the detailed feedback, it was very useful and definitely improved clarify in several sections. I applied most of your suggestions, made a couple changes and elaborated on the points you highlighted.

Let me know when you want me to take another look or if any additional actions are needed.

[DrW3RK]

Pushed the changes through https://github.com/w3f/polkadot-wiki/pull/4074

[alfarok]

@DrW3RK any specific reason you moved the content to a new PR?