Docs: add ui-block-e child element letter for grids (content-grids.html)

docs/content/content-grids.html

@@ -38,7 +38,7 @@ <h1>Layout grids</h1>
 			</ul>
 
 			<p>Grids are 100% width, completely invisible (no borders or backgrounds) and don't have padding or margins, so they shouldn't interfere with the styles of elements placed inside them. </p>
-			<p>Within the grid container, child elements are assigned <code>ui-block-a/b/c/d</code> in a sequential manner which makes each "block" element float side-by-side, forming the grid. The <code>ui-block-a</code> class essentially clears the floats which will start a new line (see multiple row grids, below).</p>
+			<p>Within the grid container, child elements are assigned <code>ui-block-a/b/c/d/e</code> in a sequential manner which makes each "block" element float side-by-side, forming the grid. The <code>ui-block-a</code> class essentially clears the floats which will start a new line (see multiple row grids, below).</p>
 
 		<h2>Two column grids</h2>
 		<p>To build a two-column (50/50%) layout, start with a container with a <code>class</code> of <code>ui-grid-a</code>, and add two child containers inside it classed with <code>ui-block-a</code> for the first column and <code>ui-block-b</code> for the second:</p>