Assorted housekeeping

[r-czajkowski]

Ref: #61

Updates made by @mswilkison 🙏.

This PR makes assorted updates and corrections to the website.

• Removes any reference to existing tBTC liquidity pools due to the imminent shutdown of renBTC and pending deployment of new pools without such exposure
• Updates various links to point to threshold docs instead of legacy nucypher docs
• Adds Balancer T + ETH pools
• Fixes description of Threshold governance
• Fixes some vote delegation links + staker vs token holder logic

[github-actions[bot]]

Preview uploaded to https://preview.threshold.network/mswilkison-pr-61/index.html.