time: remove extra space in docstring

Probably went unnoticed because HTML normalizes multiple space
characters into one, unless you explicitly ask for them with  .

Change-Id: I3f97b24a111da3f0f28894f1246388018beb084e
Reviewed-on: https://go-review.googlesource.com/54570Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Rob Pike <r@golang.org>

src/time/format.go

@@ -732,7 +732,7 @@ func skip(value, prefix string) (string, error) {
 }
 
 // Parse parses a formatted string and returns the time value it represents.
-// The layout  defines the format by showing how the reference time,
+// The layout defines the format by showing how the reference time,
 // defined to be
 //	Mon Jan 2 15:04:05 -0700 MST 2006
 // would be interpreted if it were the value; it serves as an example of