Problem: It's hard to show off Oasis or take screenshots without
respecting the `publicWebHosting` convention. While `publicWebHosting`
lacks a formal specification and I'm a bit confused about what its
boundaries are, it sounds like some of our friends would like to avoid
us publishing any of their content on the public web if we can avoid it.
Solution: Add --public option that turns Oasis into a public web viewer.
This makes it **slightly inconvenient** to see these public posts, but
should absolutely not be mistaken for a privacy guarantee. Only HTTP GET
endpoints are allowed, so random people can't publish or change
settings. The name, avatar, description, content warning, and message
contents are replaced with "Redacted", but again, this is all public
information that we can never provide real privacy for.
Resolves https://github.com/fraction/oasis/issues/48
Problem: The --offline documentation doesn't mention that networking
status can be changed, which may give the false understanding that the
networking is permanently offline when you use that flag.
Solution: Add a note that mentions that the 'meta' page lets you change
your networking status, and that --offline is only applicable to the
starting state of Oasis.
