CLI reference documentation

[andreasjansson]

Cog has reference documentation for the Python API but no reference for the command line interface. The tutorials explain parts of the CLI, but it would be great to have a single page listing all of Cog's commands and their arguments.

Topics to cover:

• [x] How to run the HTTP server
• [x] Inspecting the generated dockerfile with cog debug dockerfile
• [ ] Using the --debug flag for move verbose output

(edited by @zeke)

[zeke]

The CLI docs should probably also explain how to run the HTTP server: https://github.com/replicate/cog/issues/413#issuecomment-1043971293

[zeke]

Should probably also document $ cog debug dockerfile here too.