Removed superfluous input-group

assume this is still in the document by mistake? otherwise, why have two
email fields?
if this *was* intended to be there for some reason (to show the addon
stuff?), then this input will also need a <label class="sr-only" ...>
like the other two text/password inputs.

docs/_includes/css/forms.html

@@ -71,12 +71,6 @@ <h4>Always add labels</h4>
         <label class="sr-only" for="exampleInputEmail2">Email address</label>
         <input type="email" class="form-control" id="exampleInputEmail2" placeholder="Enter email">
       </div>
-      <div class="form-group">
-        <div class="input-group">
-          <div class="input-group-addon">@</div>
-          <input class="form-control" type="email" placeholder="Enter email">
-        </div>
-      </div>
       <div class="form-group">
         <label class="sr-only" for="exampleInputPassword2">Password</label>
         <input type="password" class="form-control" id="exampleInputPassword2" placeholder="Password">