doc: fix typo in Effective Go

Fixes issue 5329.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/8897044
net/http: make CloseNotifier channel buffered to not leak goroutines

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/8911044
time: improve the explanation of the working of Format and Parse
Change the term 'standard time', which already means something,
to 'reference time', and add a couple of sentences and clarifications.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/8799047