docs: Adding Udacity link and video to Android Material design page

Updating Android material design page with link and embedded
trailer video as per this request:

https://docs.google.com/document/d/1e5EpnHULmLZL9JCKhtblEw7VCcMNL2HMuEVkkv63Ldw/edit#

Bug: 25026005
Change-Id: I611ccdb18af6f4d3e92822b2a3dd5bba17a525b5