Enhancement: add info on starting a bis document

[ajeanmahoney]

Steps include:

• finding the original RFC file on rfc-editor.org
• converting to v3 XML using author-tools
  • or if you want to use xi:includes, convert using the command line: xml2rfc --v2v3 --add-xinclude filename
• making edits to the XML:
  • removing number="NNNN" from the <rfc> element
  • adding a docName attribute to the <rfc> element (e.g., docName="draft-foo-rfcNNNNbis-00")
  • updating the obsoletes attribute in the <rfc> element (e.g., obsoletes="NNNN")
  • removing <seriesInfo name="RFC" value="NNNN"/>
  • adding a day attribute to the <date> element (e.g., <date year="2023" month="April" day="30"/>)
• (optionally) converting XML to markdown

[ajeanmahoney]

Steps also need to cover checking the URLs used in xi:includes