[DOC] Complete documentation with _key-order (ie. _md-first) - fix example

Author: LGI@acti

docs/index.html

@@ -990,7 +990,7 @@ <h3>Normal flow with ordering (first / last) (can be based on MQ keys)</h3>
             </div>
             <div class="col_md-first">
                 <div class="demo">
-                    <p>C(_md-first)</p>
+                    <p>C (_md-first)</p>
                 </div>
             </div>
             <div class="col">
@@ -1005,11 +1005,11 @@ <h3>Normal flow with ordering (first / last) (can be based on MQ keys)</h3>
             </div>
         </div>
 <pre><code>&lt;div class="grid">
-    &lt;div class="col-last">A&lt;/div>
+    &lt;div class="col-last">A (last)&lt;/div>
     &lt;div class="col">B&lt;/div>
-    &lt;div class="col">C&lt;/div>
+    &lt;div class="col_md-first">C (first only on _md)&lt;/div>
     &lt;div class="col">D&lt;/div>
-    &lt;div class="col-first">E&lt;/div>
+    &lt;div class="col-first">E (first)&lt;/div>
 &lt;/div></code></pre>
 
         <h3>No gutter? Equal-height?</h3>