text/collate: fix 'weight' -> 'width' typo for Loose godoc

The typo is from b31968bd (text/collate: simplified API and reworked
options, 2014-11-19).

Change-Id: I8e541146726802c89502ef369811ef7f25fe8a3b
Reviewed-on: https://go-review.googlesource.com/112519
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
diff --git a/collate/option.go b/collate/option.go
index f39ef68..63569de 100644
--- a/collate/option.go
+++ b/collate/option.go
@@ -165,7 +165,7 @@
 	IgnoreWidth Option = ignoreWidth
 	ignoreWidth        = Option{2, ignoreWidthF}
 
-	// Loose sets the collator to ignore diacritics, case and weight.
+	// Loose sets the collator to ignore diacritics, case and width.
 	Loose Option = loose
 	loose        = Option{4, looseF}