The Dynamics NAV 2017 developer and IT-pro content has moved to docs.microsoft.com.
You can find the Dynamics NAV content here: https://docs.microsoft.com/en-us/dynamics-nav/
Docs.microsoft.com has been up and running for a while and now it’s time for Dynamics NAV to move this platform.
Docs.microsoft.com is the home for all Microsoft products and services docs, and it is replacing the MSDN Library.
You will also here be able to find the docs for NAV 2018, as soon as it has been released.