No, there is no proper documentation. The Civ 5 Modding Wiki is probably the closest thing you'll find, as things work very similar in Civ 5 and Beyond Earth:
http://modiki.civfanatics.com/index.php?title=Main_Page

For all the properties that can be changed, the game files are your "guide", because anything you find there, can be changed, and anything that's not there, is likely hardcoded and cannot be changed.

For simple tweaks, that's mostly the stuff in:
Sid Meier's Civilization Beyond Earth\assets\Gameplay\XML

...or in the dlc-folder if you're working with Rising Tide.

You pretty much have to get familiar with those files, because it's the "library" of basic stuff you can do. That'll take a while, but most things should be rather easy to figure out. Aside from maybe some of the GlobalDefines.

If you want to go further than that, you pretty much have to learn the Scripting Language Lua, and then get familiar with the limited version that's available in Beyond Earth.

Those files can be found in:
Sid Meier's Civilization Beyond Earth\assets\Gameplay\Lua

...for advanced stuff like editing models, and anything else that's more "out there", you'll probably need to look on places like Civfanatics.com - they have a great library of guides, mostly for Civ 5, but things largely work the same for Beyon Earth. Or you try to reverse-engineer mods other people have made.

Thanks. I figured this was the case generally, but those details are useful. Good advice.