Add sftp and webdav as repositories to "Getting started" documentation page, "Setting Up Repository" chapter.
Add repositories list and usage examples to doc.
Repository.Token() generates a base64-encoded token that can
be stored in password manager that fully describes repository connection
information (blob.ConnectionInfo) and optionally a password.
Use `kopia repo status -t` to print the token.
Use `kopia repo status -t -s` to print the token that also includes
repository password.
Use `kopia repo connect from-config --token T` to reconnect using the
token.
