collate/build: documentation fix

Fixes golang/go#19626.

Change-Id: I5801d18b435ff115a2cf3ae5b21a4917afbe4625
Reviewed-on: https://go-review.googlesource.com/44378
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
1 file changed