Accordion: Fix typo in theming documentation

Fixes gh-315

Author: scottgonzalez

entries/accordion.xml

@@ -40,7 +40,7 @@
 				<code>ui-accordion</code>: The outer container of the accordion.
 				<ul>
 					<li>
-						<code>ui-accordion-header</code>: The headers of the accordion. The active header will additionally have a <code>ui-accordion-content-active</code> class, the inactive headers will have a <code>ui-accordion-header-collapsed</code> class. The headers will also have a <code>ui-accordion-icons</code> class if they contain <a href="#option-icons"><code>icons</code></a>.
+						<code>ui-accordion-header</code>: The headers of the accordion. The active header will additionally have a <code>ui-accordion-header-active</code> class, the inactive headers will have a <code>ui-accordion-header-collapsed</code> class. The headers will also have a <code>ui-accordion-icons</code> class if they contain <a href="#option-icons"><code>icons</code></a>.
 						<ul>
 							<li><code>ui-accordion-header-icon</code>: Icon elements within each accordion header.</li>
 						</ul>