Markdown documents requirements

The source directory with markdown documents (usually named docs) must contain index.md file like the one you saw here. It isn't a true zettel, but rather an index zettel. The theme won't render it as a card with header and footer, because none is expected. The same applies to another special file called tags.md (auto-generated by mkdocs-plugin-tags).

Any markdown document representing a zettel must contain a yaml frontmatter with Zettelkasten ID (id: key), and optionally a title (title: key) and a list of tags (tags:).

Example:

---
id: 20211122110202
title: Welcome to MkDocs Zettelkasten
tags: [testing, unimportant]

---

# Welcome to MkDocs Zettelkasten

This is a zettel in form of a markdown file.

---
web: [MkDocs Zettelkasten](https://github.com/buvis/mkdocs-zettelkasten)

---