The docfx.json file points to the generated dll to be used to extract the documentation:
{ "metadata": [ { "src": [ { "src": "../src", "files": [ "lib/efl_mono/*efl_mono.dll" ] } ],
In meson builds, though, this dll is not located in the ../src folder (relative to where the docfx.json file is) but in a user-provided folder (usually build/src). Therefore, docfx.json cannot be static and has to be generated during the configure step.
Please note that generating the documentation from the source *.eo.cs files has the same problem.