doc/multi_port.svg : Update

doc/multi_plot.svg

@@ -1,7 +1,3 @@
-<?xml version="1.0" encoding="utf-8" standalone="no"?>
-<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
-  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
-<!-- Created with matplotlib (https://matplotlib.org/) -->
 <svg height="345.6pt" version="1.1" viewBox="0 0 460.8 345.6" width="460.8pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
  <metadata>
   <rdf:RDF xmlns:cc="http://creativecommons.org/ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">