Once the Android 5.1 Lollipop update is available for your Google Nexus 4, it will be seen as a system notification. Users can also manually check for it by going into Settings > About Phone > System Updates or download the zipped and Google-signed OTA update file (via 9to5Google) that has been made available online by users who have already received the update.
Unfortunately, no changelog is available for the Nexus 4's Android 5.1 update. Google started rolling out the Android 5.1 Lollipop update for Nexus devices in early March, and had only detailed changes such as support for multiple SIM cards, Device Protection and HD voice on compatible devices. However, since then, several other changes the update brings have been gleaned by users - check out our previous coverage for more details.
Meanwhile, some Google Nexus 5 users are reporting a camera crash issue after the Android 5.1 Lollipop update.
The issue is said to occur when a third-party app tries or even the default app tries to access the camera, resulting in a crash. A simple reboot reportedly fixes the issue temporarily, but then it comes back again, noted the bug report (via Android Police) filed on Google's AOSP page.
The Android 5.1 Lollipop OTA update with build number LMY47I for LG-made Google Nexus 5 weighs 220.7MB. Last month, Google had started rolling out the update to Nexus 5, but the update only reached users in India earlier this month.
Notably, these are not the only bugs that have been reported for Android 5.1 Lollipop. Apart from a memory leak issue that is still affecting users (it was first reported for Android 5.0 Lollipop back in November), some Nexus 7 and Nexus 5 users are reporting that their devices are being bricked after updating to Lollipop, with the exact version different for affected users.