Improve generate MAIN usage for rakudobrew
Improve generate MAIN usage for rakudobrew

When using rakudobrew, the MAIN function's generated usage text contains
very long paths on every line. This changes the output to showing the
full path on only one line, and then the basename on all subsequent lines.

MasterDuke17/rakudo,tony-o/rakudo,softmoth/rakudo,rakudo/rakudo,labster/rakudo,Gnouc/rakudo,raydiak/rakudo,tbrowder/rakudo,raydiak/rakudo,rakudo/rakudo,nbrown/rakudo,tbrowder/rakudo,Gnouc/rakudo,raydiak/rakudo,salortiz/rakudo,Gnouc/rakudo,jonathanstowe/rakudo,tbrowder/rakudo,softmoth/rakudo,labster/rakudo,labster/rakudo,usev6/rakudo,salortiz/rakudo,lucasbuchala/rakudo,jonathanstowe/rakudo,salortiz/rakudo,MasterDuke17/rakudo,lucasbuchala/rakudo,usev6/rakudo,lucasbuchala/rakudo,MasterDuke17/rakudo,awwaiid/rakudo,Gnouc/rakudo,lucasbuchala/rakudo,tony-o/rakudo,nbrown/rakudo,Gnouc/rakudo,sjn/rakudo,sjn/rakudo,MasterDuke17/rakudo,sjn/rakudo,rakudo/rakudo,awwaiid/rakudo,awwaiid/rakudo,sjn/rakudo,MasterDuke17/rakudo,softmoth/rakudo,awwaiid/rakudo,labster/rakudo,MasterDuke17/rakudo,labster/rakudo,nbrown/rakudo,tony-o/rakudo,tony-o/rakudo,rakudo/rakudo,usev6/rakudo,awwaiid/rakudo,raydiak/rakudo,softmoth/rakudo,usev6/rakudo,salortiz/rakudo,tony-o/rakudo,usev6/rakudo,tony-o/rakudo,tbrowder/rakudo,softmoth/rakudo,lucasbuchala/rakudo,nbrown/rakudo,Gnouc/rakudo,rakudo/rakudo,nbrown/rakudo,jonathanstowe/rakudo,sjn/rakudo,labster/rakudo,tbrowder/rakudo,jonathanstowe/rakudo,tbrowder/rakudo,nbrown/rakudo,jonathanstowe/rakudo,salortiz/rakudo,salortiz/rakudo,rakudo/rakudo