Google can confuse us with all these software update versions and build numbers but don't worry, the Android 5.1.1 isn't official yet so you can have time to catch up. Google has not yet officially announced the Android 5.1.1 release. It was only spotted on an Android Audio Latency info page showing the build numbers LMY47S and LMY47W are ready for the Nexus 9 and Nexus 7 2013 (WiFi variant).
The Google Nexus 9 has yet to receive Android 5.0 Lollipop but the Nexus 7 is already enjoying Android 5.1 despite reports of units being bricked after the software update. This Android 5.1.1 being sighted on an official Android page also means a new version is coming soon.
It may still be under development and may just be a minor but Google is set to make an announcement. Before it happens, we hope to see the Nexus 9 getting some Android 5.1 sweetness but then again it's way better if it gets the Android 5.1.1 version as its first taste of Lollipop.