Add example for accessing Nth item of a collection via data binding

[Christian Oeing]

From the forum: was wondering if there are some tutorial/sample on how to bind to collection elements? How can I bind to Nth value of collection and set its value? https://forum.unity.com/threads/released-data-bind-for-unity.298471/page-6#post-3595280

[Christian Oeing]

Added a usage to the Collection example by binding to the 2nd item of the collection

[Christian Oeing]

Removing milestone: 1.15 (automated comment)