runtime: fix docs for Caller and Callers The previous attempt to explain this got it backwards (all the more reason to be sad we couldn't make the two functions behave the same).
runtime: fix docs for Caller and Callers
The previous attempt to explain this got it backwards (all the more reason to be
sad we couldn't make the two functions behave the same).

Fixes issue 3669.

R=golang-dev, rsc
CC=golang-dev
http://codereview.appspot.com/6249051
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go