Edits to the Authentication Docs

[saberbrasher]

In the User Guide > Authentication section:

• Clicking the “interactive login method” link just reloads the same page a little further down, which is a bit odd/ doesn't serve much.
• The “Accessing session information” link doesn’t seem to work.
• In the .netrc file section: Because the file starts with a “.” on Mac, it is hidden, and users might not realize this. We should probably add notes about hidden files on Mac and how to confirm the file was created correctly.

Bonus: In my original notes on this, I had a comment that if a password contains a “!”, MacOS throws zsh: event not found: > which had tripped me up, but I can't seem to replicate the issue again... I will play with it more and see if it reemerges.