help text for submit

[glennj]

The help text for submit is no longer accurate.

$ command exercism troubleshoot
...
Current: 3.1.0
...

$ command exercism submit --help
Submit your solution to an Exercism exercise.

    Call the command with the list of files you want to submit.

Usage:
   submit FILE1 [FILE2 ...] [flags]
...

The help text still indicates at least one file is required.

(I have an "exercism" shell function: "command" bypasses it)