The Google Nexus User manual in PDF is not available yet from Google Nexus 5 Support site.
Sprint Nexus 5 owners can download the Quick start Guide,Nexus 5 Safety & Warranty from LG Official website.
The Good news is that Google’s official quick start guide on using Nexus 5 Android 4.4 KitKat is available for download right now.
You can download the free guide from Google’s Nexus support site, or from Google Play Books. The total 53 pages quick start guide gives you a good overview of how to use the KitKat flavor of Android.
Download Google Nexus 5 Guide from Google Support Site:
Download Google Nexus 5 Guide from Google Play Books: