I have noticed that only the 64 bit release of Atom is mentioned in the official documentation (e.g., https://github.com/atom/atom/releases/tag/v0.199.0), even though a ppa (which you can find here https://launchpad.net/~webupd8team/+archive/ubuntu/atom) exists for Ubuntu both 32 bit and 64 bit systems which would allow for automatic updating (as opposed to the manual updating mentioned in the documentation). Plus I know from personal experience that compiling Atom from source code (the only other way to install it on 32-bit Ubuntu) is difficult, if not impossible, hence why I would suggest updating the documentation for future users.
What you’re suggesting has been brought up multiple times.
There currently is no official Atom PPA. You can subscribe to this Issue for updates though:
When there is an official Atom PPA, I’m sure the documentation will be updated.