net/http: document Response.Body Read+Close interaction with keep-alive

Fixes #5645

Change-Id: Ifb46d6faf7ac838792920f6fe00912947478e761
Reviewed-on: https://go-review.googlesource.com/1531
Reviewed-by: David Symonds <dsymonds@golang.org>
misc/chrome/gophertool: update URLs from code.google.com to new homes

Change-Id: I46bf9f1b84a331cabce2d3417b2b59ccb83d00fa
Reviewed-on: https://go-review.googlesource.com/1532
Reviewed-by: David Symonds <dsymonds@golang.org>