improve function argument names in docs for a bunch of functions

[zeen]

These now either match the source code (e.g., ST_MakeEnvelope()), or match the description in the docs (geom1, geom2).

[Maxxen]

Hi! Thanks a lot for this PR and the help on improving the docs.
This should probably also be documented (ha), but the source-of-truth for the function reference is in the c++ files themselves, the markdown itself is generated by executing the generate_function_reference.py script in the root of the directory.

To add function parameter names for e.g. ST_MakeEnvelope you'd have to add

DocUtil::AddFunctionParameterNames(db, "ST_MakeEnvelope", {"min_x", "min_y", "max_x", "max_y"});

after the RegisterFunction call in e.g. src/spatial/core/functions/scalar/st_makeenvelope.cpp:58. Then recompile and execute the generate_funciton_reference.py script.

If this seems like a lot of effort feel free to leave this PR open as is and I will try to pick it up and incorporate the changes next time im working on spatial!

We're planning to rework this in the future so that all functions are declared separately with their names/parameters/types/overloads/descriptions/examples in e.g. json files from which we can generate both the markdown docs and scaffold the c++ stubs from.