Looks like they removed every content that is not related with development for desktop. For example when you click in "Get Started" tab there is only information about the Ubuntu Touch and its SDK, when you click on "Resources" tab and then on "Programming languages" you only see C++, JavaScript and QML (no Python, Java, Mono, etc). You also can't find any information about Quickly, try clicking on "Quicky" at "Resources" in the website bottom and you will see a "Page not found" error.
Is the site under maintenance or something else?
Best Answer
As part of the process of making Ubuntu a truly convergent platform, where the apps that you develop can run on any device or form factor, we've started the process of focusing the content on the App developer site to be about the Ubuntu SDK.
While Quickly will still be available and open to community participation and maintenance, the recommended way to develop apps for Ubuntu is the Ubuntu SDK.
This has been discussed at the last two virtual UDSs and you can track the progress and provide feedback on this blueprint