Out of the box, the default flag.FlagSet variable, flag.CommandLine, will print usage information and exit 0 if -h or -help is given and a flag with that name was not already registered. This nicety feature is great, however I discovered by surprise! Looking through the flag documentation at 1.22.2, I found mention of the -h and -help flags in ErrHelp's documentation, but nothing at the package level or on CommandLine specifically about this default behavior.

ErrHelp is the error returned if the -help or -h flag is invoked but no such flag is defined.

I am happy to open a PR to improve documentation in this area if it would be well receive :).