Setup threshold canister on mainnet and update documentation

[aodl]

• Setup threshold canister on mainnet and update documentation.
• Decentralise control to a large number of collaborators
• Blackhole the minor canisters

[aodl]

Threshold canister -> https://dashboard.internetcomputer.org/canister/basbh-oyaaa-aaaar-qbxha-cai
Readme has been updated