clarified the 'set a maximum size for embedded resources' description

extension/ui/pages/help.html

@@ -369,7 +369,8 @@
 
 					<li>
 						<span class="option">set a maximum size for embedded resources (MB)</span>
-						<p>Specify the maximum size of embedded resources (i.e. images, stylesheets, scripts and iframes) in megabytes.
+						<p>Specify the maximum size of each embedded resources (i.e. images, stylesheets, scripts and iframes) in
+							megabytes.
 						</p>
 					</li>