Add note on PEP8 analogy

guidelines/markdown.md

 These are not meant as strict rules, but rather set of hints, and
 reminders for myself next time I forget how do I do spacing etc.
 
+If you are familliar with Python, especially PEP8, you can think of
+this document as my personal PEP8-for-Markdown.
+
 The guidelines take only original MD into account.