[readme] Improve README about Macs with M1 chips
[readme] Improve README about Macs with M1 chips

Mention that you must have Rosetta 2 installed and provide instructions on how to do it.

PeterDaveHello/nvm,ljharb/nvm,creationix/nvm,ljharb/nvm,PeterDaveHello/nvm,creationix/nvm