language: fix typo in update docs

Change-Id: Ied188b87f0a9a1a4fb160b2a7ba239ed70b843a6
Reviewed-on: https://go-review.googlesource.com/c/text/+/359715
Reviewed-by: Ian Lance Taylor <[email protected]>
Reviewed-by: Amelia Downs <[email protected]>
Trust: Cherry Mui <[email protected]>

Author: ameowlia

language/match.go

@@ -545,7 +545,7 @@ type bestMatch struct {
 // match as the preferred match.
 //
 // If pin is true and have and tag are a strong match, it will henceforth only
-// consider matches for this language. This corresponds to the nothing that most
+// consider matches for this language. This corresponds to the idea that most
 // users have a strong preference for the first defined language. A user can
 // still prefer a second language over a dialect of the preferred language by
 // explicitly specifying dialects, e.g. "en, nl, en-GB". In this case pin should