Redirect subpages of https://tbtc.network #95
Description
When googling tbtc docs one of the first results I get directs me to this page with an outdated documentation: https://tbtc.network/pl/developers/. It looks that we have https://tbtc.network pointing to https://threshold.network/earn/btc/, but don't have any redirections set up for https://tbtc.network/developers/ and similar subpages. We should make sure all the addresses of the old docs redirect to current docs.