It is not that long when Apple realeased iOS 11 for public. In few day we can update to 11.0.1 with lot of fix for security, animations, stability, performance, etc.. It is not something strange, iOS 11.1 is now available for developers.

How to update to iOS 11.0.1

In case that your iDevice does not show any notice, you can go to Settings->General->Software Update. If you have installed “iOS Beta Software Profile” you should remove it or update to iOS 11.0.1 with iTunes.

More: https://support.apple.com/kb/ht201222