[css-align] Fix the initial value for align-items.

Author: tabatkins

css-align/Overview.bs

@@ -990,7 +990,7 @@ Block/Cross-Axis Alignment: the 'align-items' property</h3>
 	<pre class="propdef">
 	Name: align-items
 	Value: normal | stretch | <<baseline-position>> | [ <<overflow-position>>? && <<self-position>> ]
-	Initial: auto
+	Initial: normal
 	Applies to: block-level elements
 	Inherited: no
 	Percentages: n/a