code: public void pi(Map<String, Map<String, Object>> args) {
          builder.pi(args);
      }
docs: Produce an XML processing instruction in the output.
  For example:
  <pre>
  mkp.pi("xml-stylesheet":[href:"mystyle.css", type:"text/css"])
  </pre>
  
  @param args a map with a single entry whose key is the name of the
  processing instruction and whose value is the attributes
  for the processing instruction.