This Marshmallow ROM, Android M for Nexus 4 is brought to you by Dmitry Grinberg. Google is not supporting Android 6.0 Marshmallow for Nexus 4 and hence this is an unofficial build.
Installing custom ROM requires a custom recovery to be installed on your device, which may VOID your warranty and may delete all your data. Before proceeding further you may consider backup your all data. Understand that YOU are the only person making changes to your phone. Neither we nor the developer can be held responsible for the disaster that may happen to your device after following this guide.
Recommended files for Android M for Nexus 4 ROM installation: