[selectors] Consistently use plurals. Fixes #162.

Author: tabatkins

selectors/Overview.bs

@@ -1902,14 +1902,14 @@ The Target Pseudo-class: '':target''</h3>
 	</div>
 
 	The <dfn id='target-pseudo'>:target</dfn> pseudo-class matches the document's target elements.
-	If the document's URL has no fragment identifier, then the document has no target element.
+	If the document's URL has no fragment identifier, then the document has no target elements.
 
 	<div class="example">
 		Example:
 
 		<pre>p.note:target </pre>
 
-		This selector represents a <a element>p</a> element of class
+		This selector represents a <{p}> element of class
 		<code>note</code> that is the target element of the referring
 		URL.
 	</div>