class secondary referenced, but not defined in css/less

Not sure if this is an issue per se, but I noticed line 1157 in docs/index.html

```
         <div class="modal-footer">
            <a href="#" class="btn primary">Primary</a>
            <a href="#" class="btn secondary">Secondary</a>
          </div>
```

the .primary class is defined, but not the .secondary class.  Is this intentional?
