Be a bit more specific about where the private key and public key should
be stored when generating a new GPG key for a journalist.
Correct the path to the directory we want the admin to be in when
installing SecureDrop
Explain the purpose of the passphrases section in install.md. Ideally,
we should provide a template database for the admin and journalist to
use, but clarifying that the list is a checklist one can use during the
installation process is better than nothing. Solves #762.
Attempt to list the information required by prod-specific.yml for a
SecureDrop install. Solves #745.
Merge pull request #767 from runasand/develop

Additional updates for install.md