ShowHelp upon hook running

[JoshuaTheMiller]

Hookboy should display help text after every hook.
In light gray so as to not be too distracting.
Should be able to be turned off by running hookboy config set ShowHelp false (ShowHelp must be uppercase)
Should be able to be turned off when first installing hooks by running hookboy install --do-not-show-help
Subsequent runs of hookboy install should not modify any past set config values