docs: RFC proposal to center talk about authentication around

[bcoe]

I don't have particularly strong opinions about how authentication is implemented in yarn, but I've had a few customers ask after it already, and there are a few threads in the yarn issue tracker on the subject (yarnpkg/yarn#521, yarnpkg/yarn#547).

I thought it would be worthwhile to center this discussion around an RFC; it's a complicated enough feature that context could easily be lost across open GitHub issues.

[joshmanders]

Yes! I would like to see something that supports context switching. I have a tool that I wrap around npm right now that allows me to login to multiple accounts and switch out the authentication token depending on a --as flag. Since I publish modules under my own account and employers account, sometimes it gets cumbersome logging out and into new accounts to make the changes, then back.

[ljharb]

I do the same with an alias that moves around .npmrc files. It'd be great to have yarn more transparently use npm configs as opposed to inventing a non-drop-in way to configure things.

[ashleygwilliams]

relevant: yarnpkg/yarn#839

tl;dr this PR implements using a .npmrc file to auth to private registry

a bunch of people on the discord have been saying they've successfully used that branch to link yarn with their private registry.

[bcoe]

@ashleygwilliams yarnpkg/yarn#839 seems like a great approach to implementing authentication; Supporting multiple registries is definitely the best-case scenario.

[bcoe]

It looks like @devongovett has pulled together a wonderful implementation of authentication/multiple-registry-support. Closing this RFC, and calling it a fun experiment 👍