Q1
A help catalog with a more detailed information about the warning would be a great addition.
Q2
Making help and warning info accessible via the elixir command would be another great addition.
Q3
This would be the natural progression of 2, so I vote for this too.
One suggestion I have is to not restrict the help catalog to just warnings. It would be great if we could expose other kinds of useful information which is usually shoved into a README or Getting Started guide via the help catalog. Take distillery for example, it would be great if we could list all the topics in a help catalog for distillery by something like elixir -h 'distillery:*' and then get detailed info on elixir -h distillery:getting_started or elixir -h distillery:phoenix.
