io: document ReaderFrom #3711
Description
The docs on ReaderFrom are very light: http://golang.org/pkg/io/#ReaderFrom ` type ReaderFrom interface { ReadFrom(r Reader) (n int64, err error) } ReaderFrom is the interface that wraps the ReadFrom method. ` But it doesn't say what the method is expected to do. The *bytes.Buffer ReadFrom provides some clues: http://golang.org/pkg/bytes/#Buffer.ReadFrom ... but is that the promise from a *bytes.Buffer, or of all ReadersFrom?