help: description of fmt is now inaccurate

[ee7]

The description says only "Format the exercise '.meta/config.json' files":

$ bin/configlet --help
configlet 4.0.0-beta.11
The official tool for managing Exercism language track repositories.

Usage:
  configlet [global-options] <command> [command-options]

Commands:
  completion  Output a completion script for a given shell
  fmt         Format the exercise '.meta/config.json' files
  generate    Generate Concept Exercise 'introduction.md' files from 'introduction.md.tpl' files
  [...]

but since 72f865b, it also operates on .approaches/config.json and .articles/config.json.