feat(cli.ts): enhance fgm flag to include description and default value for better usability

[kakakakakku]

Summary

Thank you for such a great tool😀

I noticed that the --fgm option in the oco command help output does not have a description:

The motivation of this pull request is to improve the clarity of the help message by adding a description for the --fgm flag.

Before

$ oco -h
opencommit v3.2.7

Auto-generate impressive commits in 1 second. Killing lame commits with AI 🤯🔫

Usage:
  opencommit [flags...]
  opencommit <command>

Commands:
  config
  hook
  commitlint

Flags:
  -c, --context <string>        Additional user input context for the commit message
      --fgm
  -h, --help                    Show help
      --version                 Show version
  -y, --yes                     Skip commit confirmation prompt

After

$ oco -h  
opencommit v3.2.7

Auto-generate impressive commits in 1 second. Killing lame commits with AI 🤯🔫

Usage:
opencommit [flags...]
opencommit <command>

Commands:
config                                                                                                                                                                                                  
hook                                                                                                                                                                                                    
commitlint                                                                                                                                                                                              

Flags:
-c, --context <string>        Additional user input context for the commit message                                                                                                                      
    --fgm                     Use full GitMoji specification                                                                                                                                            
-h, --help                    Show help                                                                                                                                                                 
    --version                 Show version                                                                                                                                                              
-y, --yes                     Skip commit confirmation prompt    

Could you please review? Thanks a lot 👍