Update README.md

[wheresaddie]

updated terms, added WIP chains and corrected some information around alternative ecosystems-- also it is worth noting that many of these new PoS are technically much more stable and advanced than ETH/BTC so I removed the clause around 'However, this is likely to have other issues. Such platforms are likely to not have had the time or investment to be as developed, polished or user friendly as the older, more established Ethereum based platforms."

as this is completely incorrect, many of these have dramatically more investment both in dev hours and fiat funding :)

[wheresaddie]

please review and merge if approved @memo