Update docs

Author: marcaaron

API.md

@@ -76,6 +76,7 @@ Subscribes a react component's state directly to a store key
 | [mapping.withOnyxInstance] | <code>Object</code> | whose setState() method will be called with any changed data      This is used by React components to connect to Onyx |
 | [mapping.callback] | <code>function</code> | a method that will be called with changed data      This is used by any non-React code to connect to Onyx |
 | [mapping.initWithStoredValues] | <code>Boolean</code> | If set to false, then no data will be prefilled into the  component |
+| [mapping.waitForCollectionCallback] | <code>Boolean</code> | If set to true, it will return the entire collection to the callback as a single object |
 
 **Example**
 ```js

lib/Onyx.js

@@ -412,7 +412,7 @@ function sendDataToConnection(config, val, key) {
  *      This is used by any non-React code to connect to Onyx
  * @param {Boolean} [mapping.initWithStoredValues] If set to false, then no data will be prefilled into the
  *  component
- * @param {Boolean} [mapping.waitForCollectionCallback] If set to true, it will trigger the callback once and return all data as a single object
+ * @param {Boolean} [mapping.waitForCollectionCallback] If set to true, it will return the entire collection to the callback as a single object
  * @returns {Number} an ID to use when calling disconnect
  */
 function connect(mapping) {