Simulation_SPICE: Add ngspice manual links
Added Datasheet links into the relevant ngspice manual section for most Simulation_SPICE symbols.
The references are using LyX labels from the ngspice manual source to ensure the references should be as stable as possible (https://sourceforge.net/p/ngspice/ngspice-manuals/ci/master/tree/manual.lyx)
Example: https://ngspice.sourceforge.io/docs/ngspice-html-manual/manual.xhtml#cha_JFETs