all: spelling tweaks, A-G

LGTM=ruiu, bradfitz
R=golang-codereviews, bradfitz, ruiu
CC=golang-codereviews
https://golang.org/cl/91840044

conn.go

@@ -82,7 +82,7 @@ func (c *Conn) SetReadDeadline(t time.Time) error {
 	return c.conn.SetReadDeadline(t)
 }
 
-// SetWriteDeadline sets the write deadline on the underlying conneciton.
+// SetWriteDeadline sets the write deadline on the underlying connection.
 // A zero value for t means Write will not time out.
 // After a Write has timed out, the TLS state is corrupt and all future writes will return the same error.
 func (c *Conn) SetWriteDeadline(t time.Time) error {