docs: add explanation for the C badge

Closes #5120

misc/demo/index.html

@@ -197,6 +197,7 @@
 
                         <ul>
                             <li><i class="glyphicon glyphicon-eye-open"></i> - This setting has an angular $watch listener applied to it.</li>
+                            <li><small class="badge">C</small> - This setting can be configured globally in a constant service*.</li>
                             <li><small class="badge">$</small> - This setting expects an angular expression instead of a literal string. If the expression support a boolean, you can pass it directly.</li>
                             <li><small class="badge">readonly</small> - This setting is readonly.</li>
                         </ul>
@@ -205,7 +206,7 @@
                         For the services (you will recognize them with the <code>$</code> prefix), we list all the possible parameters you can pass to them and their default values if any.
                     </p>
                     <p>
-                        Also, some components have default values that you can override globally within a <code>.config</code> function for example.
+                        * Some directives have a config service that follows the next pattern: <code>uibDirectiveConfig</code>. The service's settings use camel case. The services can be configured in a <code>.config</code> function for example.
                     </p>
                 </section>
                 <% demoModules.forEach(function(module) { %>