[css-grid] Fix grammar error in auto-track-list. <https://lists.w3.org/Archives/Public/www-style/2016May/0189.html>

Author: fantasai

css-grid/Overview.bs

@@ -1212,8 +1212,8 @@ Explicit Track Sizing: the 'grid-template-rows' and 'grid-template-columns' prop
 
 	<pre>
 		<dfn>&lt;track-list></dfn>         = [ <<line-names>>? [ <<track-size>> | <<track-repeat>> ] ]+ <<line-names>>?
-		<dfn>&lt;auto-track-list></dfn>    = [ <<line-names>>? [ <<fixed-size>> | <<fixed-repeat>> ] ]+ <<auto-repeat>>
-		                       [ <<line-names>>? [ <<fixed-size>> | <<fixed-repeat>> ] ]+ <<line-names>>?
+		<dfn>&lt;auto-track-list></dfn>    = [ <<line-names>>? [ <<fixed-size>> | <<fixed-repeat>> ] ]* <<line-names>>? <<auto-repeat>>
+		                       [ <<line-names>>? [ <<fixed-size>> | <<fixed-repeat>> ] ]* <<line-names>>?
 
 		<dfn>&lt;track-size></dfn>         = <<track-breadth>> | minmax( <<inflexible-breadth>> , <<track-breadth>> ) | fit-content( [ <<length>> | <<percentage>> ] )
 		<dfn>&lt;fixed-size></dfn>         = <<fixed-breadth>> | minmax( <<fixed-breadth>> , <<track-breadth>> ) | minmax( <<inflexible-breadth>> , <<fixed-breadth>> )