There is an unofficial documentation site maintained by a developer called unanancyowen that enables SDK 2.0 documentation information to easily be searched with menus at the top of the page. The site is generated by accessing the official documentation pages and presenting the information in a more easily searchable interface.
If you wish to see the official SDK 2.0 documentation, it can be viewed at this page:
This message was posted on behalf of Intel Corporation
The documentation Marty has shared with you is very useful. Additionally in the following link you will find all the documentation related to the D400 cameras:
Hope this helps.