reflect: fix stale Value.kind documentation
reflect: fix stale Value.kind documentation

The lowests fives bits are the kind, and the next five bits are attributes,
not the other way around.

Change-Id: I5e1d13b195b766e99f66bb1227cc7f84e85dc49d
Reviewed-on: https://go-review.googlesource.com/c/go/+/425185
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@google.com>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@google.com>
Reviewed-by: Daniel Martí <29bf28b42a938ace12a5819da4ed4ba03d82f315@mvdan.cc>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
Auto-Submit: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>

golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go