[css-tables] Editorial fix

Just to get bikeshed to update the spec =)

Author: FremyCompany

css-tables-3/Overview.bs

@@ -46,7 +46,7 @@ spec:css22; type:property; text:display
 -->
 <h2 id="intro">Introduction</h2>
 
-	<em>This section is not normative</em></p>
+	<em>This section is not normative</em>
 
 	Many types of information (ex: weather readings collected over the past year)
 		are best visually represented in a two-axis grid