document svg generation and purpose

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 lookup kernel's view of pinouts on different boards (useful for device tree and gpio debugging)
 
+
+It supports simple one or two row pin headers with 2.54mm pin spacing which are specified in
+simple text form at end of file based on model derived from device tree.
+
+This tool also creates svg pinouts which you can print out with correct 2.54mm spacing and put
+on your board to make wiring easier.
+
+
+For device tree information, best source right now is this presentation:
 https://elinux.org/images/d/dc/Elce_2017_dt_bof.pdf