Update 8-fungsi-copy.go

[rohmanhm]

The builtin copy(dst, src) copies min(len(dst), len(src)) elements.

So if your dst is one, only one element will be copied.

https://golang.org/ref/spec#Appending_and_copying_slices

The number of elements copied is the minimum of len(src) and len(dst).

[rohmanhm]

I put the playground here.
https://play.golang.org/p/GqtRKhupuct

[novalagung]

Thank you. I put additional explanation and example to avoid some confusions to new users.
The book will be updated in few minutes.