[css-align] Fix w3c#1396, ambiguity of section end.

Author: fantasai

css-align/Overview.bs

@@ -48,8 +48,6 @@ table.align-details { width: 100%; }
 <h2 id="intro">
 Introduction</h2>
 
-	<em>This section is not normative.</em>
-
 	CSS Levels 1 and 2 allowed for the alignment of text via 'text-align'
 	and the alignment of blocks by balancing ''margin/auto'' margins.
 	However, except in table cells,
@@ -66,6 +64,8 @@ Introduction</h2>
 	If implementors or anyone else notices a discrepency,
 	please report this to the CSSWG as an error.
 
+	<em>This section (above) is not normative.</em>
+
 <h3 id="placement">
 Module interactions</h3>