Add manager options link to macos install (en)

[VagishVela]

This clarifies the options for MacOS, but maybe not to the extent that #2874 wants.

This adds the rvm and rbenv options so if someone comes from google they know those can use used for mac similar to https://www.ruby-lang.org/en/downloads/.

I think this would be a start and at least helps people coming there for now.