net/http: document that body is closed after (*Request).Write. Fixes issue 6911.
net/http: document that body is closed after (*Request).Write.
Fixes issue 6911.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/38690043

pombredanne/go-deleteme,pombredanne/go-deleteme,tv42/old-go,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,pombredanne/go-deleteme,pombredanne/go-deleteme,tv42/old-go,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,tv42/old-go,tv42/old-go