The options have no tags. NewFlag(codec, name, description) and
NewArgument(codec, name, description) define the inputs; WithField binds each
value to its options field. Application and command constructors accept the same
optional name/description strings, without a codec argument. Multiple description
parts are joined with spaces.
Run from the repository root:
mise example builder-fields World
# Hello, World!
mise example builder-fields -g Hey Carl
# Hey, Carl!
mise example builder-fields --help