Poetry: List all commands with --help flag

[chdsbd]

• [x] I have searched the issues of this repo and believe that this is not a duplicate.
• [x] I have searched the documentation and believe that my question is not covered.

Feature Request

I think it would be helpful to provide a list of valid commands with poetry --help, like poetry list does. I think this would require merging the functionality of list into the poetry --help command.

[sdispater]

This is already the case for the 1.0.0 prereleases. Basically the list command is gone and poetry --help displays the available commands.