doc: finish net/http notes in go1.3.html
doc: finish net/http notes in go1.3.html

LGTM=r
R=r
CC=golang-codereviews
https://codereview.appspot.com/86580043

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