note about foreach returning Unit

Author: toy

_overviews/cheatsheets/index.md

@@ -482,8 +482,9 @@ println(upper.getOrElse(""))</code></pre></td>
       <pre class="highlight"><code>option match {
   case Some(x) =&gt; f(x)
   case None    =&gt; ()
-}</code></pre></td>
-      <td>Apply a procedure on optional value</td>
+}
+()</code></pre></td>
+      <td>Apply a procedure on optional value. Returns <code>Unit</code></td>
     </tr>
     <tr>
       <td><pre class="highlight"><code>option.fold(y)(f(_))</code></pre>