improve OS nomenclature under releases page?

[alan707]

Maybe other people will find it useful as well. The nomenclature of the different OS releases is a bit counterintuitive for OSX users. Windows and Linux are clear, but how about changing the name from Darwin to OSX?

I am happy to add an explanation on how you can figure out if you have AMD or ARM in your system.

[diwakergupta]

Sure, feel free to send a PR!

[alan707]

@diwakergupta I've sent a PR to improve installation instructions on README.MD keeping the current nomenclature: https://github.com/dropbox/dbxcli/pull/82