What is a custom Android Nougat CD - ROM and how do you 'drop' it on a Nexus 5? Sounds dangerous!

[AC Question]

My wife has a Nexus 5, which will not be updated automatically.

 

[belodion]

Are you referring to this? http://m.androidcentral.com/will-my-phone-get-updated-android-nougat

It just means downloading the ROM via a PC. Not ready yet though.
I have a Nexus 5 myself and may consider it.