[css-multicol-2] add missing brackets

Author: rachelandrew

css-multicol-2/Overview.bs

@@ -686,7 +686,7 @@ The number and size of columns</h2>
 	</ul>
 
 	A third property, 'columns',
-	is a shorthand property which sets both 'column-width' and 'column-count'.
+	is a shorthand property which sets 'column-width' and 'column-count', and 'column-height'.
 
 	Other factors, such as explicit column breaks, content, and height constraints,
 	may influence the actual number and width of columns.
@@ -965,7 +965,7 @@ The number and size of columns</h2>
 
 	<pre class="propdef shorthand">
 	Name: columns
-	Value: <<'column-width'>> || <<'column-count'>> [ / <<'column-height'>> ]?
+	Value: [ <<'column-width'>> || <<'column-count'>> ] [ / <<'column-height'>> ]?
 	</pre>
 
 	This is a shorthand property for setting 'column-width', 'column-count',