add ODD specs and guidelines for biblio

[SteffenAstheimer]

Guidelines:

• top level elements
  • analytic
  • monogr
  • series
  • keywords
  • note
• other elements
  • biblStruct
  • ?
• specifics cases depending on type
  • book
  • mastersthesis
  • phdthesis
  • score
  • inbook
  • incollection
  • inproceedings
  • online
  • misc

Specs:

• required / forbidden top level elements depending on type
• note
• ?