fix: Set cssClass as optional in documentation

Author: pixelastic

README.md

@@ -145,10 +145,7 @@ search.addWidget(
       {name: 'instant_search_price_asc', label: 'Lowest price'},
       {name: 'instant_search_price_desc', label: 'Highest price'}
     ],
-    htmlAttributes: {
-      id: 'indexSelectorDropdown',
-      class: 'form-control'
-    }
+    cssClass: 'form-control'
   })
 );
 ```
@@ -158,7 +155,7 @@ search.addWidget(
  * Instantiate a dropdown element to choose the current targeted index
  * @param  {String|DOMElement} options.container Valid CSS Selector as a string or DOMElement
  * @param  {Array} options.indices Array of objects defining the different indices to choose from. Each object must contain a `name` and `label` key.
- * @param  {String} [options.htmlAttributes] Object of html attributes to be passed to the generated `select` element
+ * @param  {String} [options.cssClass] Class name(s) to be added to the generated select element
  * @return {Object}
  */
 ```

widgets/index-selector.js

@@ -7,7 +7,7 @@ var utils = require('../lib/widget-utils.js');
  * Instantiate a dropdown element to choose the current targeted index
  * @param  {String|DOMElement} options.container Valid CSS Selector as a string or DOMElement
  * @param  {Array} options.indices Array of objects defining the different indices to choose from. Each object must contain a `name` and `label` key.
- * @param  {String} options.cssClass Class name(s) to be added to the generated select element
+ * @param  {String} [options.cssClass] Class name(s) to be added to the generated select element
  * @return {Object}
  */
 function indexSelector({
@@ -18,7 +18,7 @@ function indexSelector({
   var IndexSelector = require('../components/IndexSelector');
   var containerNode = utils.getContainerNode(container);
 
-  var usage = 'Usage: indexSelector({container, indices[, htmlAttributes]})';
+  var usage = 'Usage: indexSelector({container, indices[, cssClass]})';
   if (container === null || indices === null) {
     throw new Error(usage);
   }