[css-grid] Swap min()/max() to be correct. Fixes w3c#4789.

Author: tabatkins

css-grid-1/Overview.bs

@@ -1555,7 +1555,7 @@ Track Sizes</h4>
 		<dt><dfn lt="fit-content()">fit-content( <<length-percentage>> )</dfn>
 		<dd>
 			Represents the formula
-			<code>min(<var>minimum</var>, max(<var>limit</var>, ''max-content''))</code>,
+			<code>max(<var>minimum</var>, min(<var>limit</var>, ''max-content''))</code>,
 			where <var>minimum</var> represents an ''grid-template-columns/auto'' minimum
 			(which is often, but not always, equal to a ''min-content'' minimum),
 			and <var>limit</var> is the <a>track sizing function</a>