cmd/doc: if no top-level symbols match, look for methods
Improving the usability further.
Before:
$ go doc bytes.Read
doc: symbol Read not present in package bytes installed in "bytes"
$
After:
$ go doc bytes.Read
func (b *Buffer) Read(p []byte) (n int, err error)
Read reads the next len(p) bytes from the buffer or until the buffer is drained.
The return value n is the number of bytes read. If the buffer has no data to
return, err is io.EOF (unless len(p) is zero); otherwise it is nil.
func (r *Reader) Read(b []byte) (n int, err error)
$