docs: verilog_a_system_functions.md incorrectly claims only gmin is handled as $simparam

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Problem

verilog_a_system_functions.md states:

"JAX only handles gmin. Models using scale, tnom, or iteration-dependent behavior may differ."

And the gap analysis lists tnom, scale, iteration as "Currently Missing in JAX Path".

Reality

vajax.SIMPARAM_DEFAULTS (in openvaf_models.py) handles a full set of simparam values including:
gmin, tnom, scale, abstol, reltol, vntol, imax, iniLim, iteration, gdev, sourceScaleFactor, shrink, $abstime, $mfactor, $analysis_type.

The entire "gap analysis" section of this document is outdated and misleading.