Many people across the Known World have written articles, created templates, and otherwise provided resources for people learning how to document. Here are just a few of them.
A&S Documentation: What Do They Want? by Mistress Ealasaid nic Suibhne
Lays out a nice progression of examples of documentation from ‘none’ to ‘thorough’ with explanations as to what is missing and what has improved.
An Approach to Documentation by Mistress Ailis ingen Mheadhbha.
Notes from a class on doing research and documentation before making the physical item.
Arts and Sciences Documentation Questionnaire by Antonia di Lorenzo
A series of straightforward questions designed to produce a reasonably thorough piece of documentation.
Documenting Arts and Sciences Entries by (probably) Mistress Eleanora van den Boegarde (author unconfirmed)
An article on the purpose of documentation and how to do it.
Finally, Drachenwald’s A&S judging criteria for specific crafts might help you think through additional things you might want to discuss, based on your A&S area.