all: single space after period.

The tree's pretty inconsistent about single space vs double space
after a period in documentation. Make it consistently a single space,
per earlier decisions. This means contributors won't be confused by
misleading precedence.

This CL doesn't use go/doc to parse. It only addresses // comments.
It was generated with:

$ perl -i -npe 's,^(\s*// .+[a-z]\.)  +([A-Z]),$1 $2,' $(git grep -l -E '^\s*//(.+\.)  +([A-Z])')
$ go test go/doc -update

Change-Id: Iccdb99c37c797ef1f804a94b22ba5ee4b500c4f7
Reviewed-on: https://go-review.googlesource.com/20022
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Dave Day <djd@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

tls_test.go

@@ -199,7 +199,7 @@ func TestDialTimeout(t *testing.T) {
 func TestConnReadNonzeroAndEOF(t *testing.T) {
 	// This test is racy: it assumes that after a write to a
 	// localhost TCP connection, the peer TCP connection can
-	// immediately read it.  Because it's racy, we skip this test
+	// immediately read it. Because it's racy, we skip this test
 	// in short mode, and then retry it several times with an
 	// increasing sleep in between our final write (via srv.Close
 	// below) and the following read.