The Prepar3D SDK is now available on the download page!
http://www.prepar3d.com/downloads/
The SDK documentation is now part of the new Learning Center launcher. After installation of the SDK, a shortcut will appear in your Start Menu called ‘SDK Learning Center.’ This can also be found in the SDK installation directory in \LC\LearningCenter.exe
You can choose an article, select the Add to Favorites Star, and customize your own SDK articles in the ‘Favorites’ section.
Here is a screenshot:
Enjoy!