There’s no obvious way to find the CE documentation, and it seems like CE is being replaced by EE, but with some painstaking effort I managed to stumble upon some CE documentation, so I think it’s most likely just a documentation bug and not a sign that CE is being phased out?
I can see where this can create confusion. There were neither changes to the CE or EE edition nor are there any changes planned in phasing one or the other. Both remain the same.
In short, you get exactly the same functionality installing either package. The only difference is the license (CE is open source, and EE is proprietary), and the fact that when you purchase a license key, it unlocks the extra functions of the EE package.
Thus the installation page shows an opinionated choice to simplify the installation instructions and to recommend EE to make it easier to unlock the extra functions if desired. Those who prefer using a package with an open source license, can simply install CE as usual.
This page explains the above in more detail:
I think where we could do a better job is in making this explanation more visible on the installation page. If you look at the screenshot of the installation page, it does have a link to the ce-or-ee page above, but it is not very visible and easy to miss.