[css-grid] Remove dangling references to flex values as minimums

Author: fantasai

css-grid/Overview.bs

@@ -1252,9 +1252,11 @@ Explicit Track Sizing: the 'grid-template-rows' and 'grid-template-columns' prop
 			and less than or equal to <var>max</var>.
 			If <var>max</var> &lt; <var>min</var>,
 			then <var>max</var> is ignored and ''minmax(min,max)'' is treated as <var>min</var>.
-			As a maximum, a <<flex>> value sets the track's <a>flex factor</a>.
-			As a minimum, it is treated as zero
-			(or ''min-content'', if the <a>grid container</a> is sized under a <a>min-content constraint</a>).
+			As a maximum, a <<flex>> value sets the track's <a>flex factor</a>;
+			it is invalid as a minimum
+
+			Note: A future level of this spec may allow <<flex>> minimums,
+			and will update the <a>track sizing algorithm</a> to account for this correctly
 
 		<dt><dfn>auto</dfn>
 		<dd>
@@ -1505,8 +1507,6 @@ Flexible Lengths: the ''fr'' unit</h4>
 
 	Each column or row's share of the <a>free space</a> can be computed as the column or row's
 	<code>&lt;flex> * &lt;free space> / &lt;sum of all <a>flex factors</a>&gt;</code>.
-	For the purpose of this calculation,
-	a flexible length in the <var>min</var> position of a ''minmax()'' function is treated as ''0'' (an inflexible length).
 
 	Note: If the sum of the <a>flex factors</a> is less than 1,
 	they'll take up only a corresponding fraction of the <a>free space</a>,