[selectors-nonelement] Reintroduced text lost during merge

Author: Jirka Kosek

selectors-nonelement/Overview.bs

@@ -65,4 +65,5 @@ Attribute node selector</h3>
 
 	</div>
 
-	In CSS, <a>attribute node selectors</a> never generate boxes.
+	Although entirely valid in Selectors used in the scope of CSS,
+	<a>attribute node selectors</a> never generate boxes.

selectors-nonelement/Overview.html

@@ -177,7 +177,8 @@ <h3 class="heading settled heading" data-level=2.1 id=attribute-node-selector><s
 </pre>
 	</div>
 
-<p>	In CSS, <a data-link-type=dfn href=#attribute-node-selector0 title="attribute node selectors">attribute node selectors</a> never generate boxes.
+<p>	Although entirely valid in Selectors used in the scope of CSS,
+	<a data-link-type=dfn href=#attribute-node-selector0 title="attribute node selectors">attribute node selectors</a> never generate boxes.
 
 <h2 class="no-ref no-num heading settled heading" id=conformance><span class=content>
 Conformance</span><a class=self-link href=#conformance></a></h2>