Project with subfolders

[seniorGolang]

Hi!
How I can use it for project with subfolders?

Now I have this:
bash-3.2$ go-selfupdate projectName 1.0.0
read projectName/config: is a directory
panic: read projectName/config: is a directory

goroutine 1 [running]:
main.createUpdate(0xc820082440, 0x14, 0xc82008204f, 0x5)
/Users/alex/go/src/github.com/sanbornm/go-selfupdate/main.go:80 +0x6b3
main.main()
/Users/alex/go/src/github.com/sanbornm/go-selfupdate/main.go:176 +0x65d