Add a <code>◊note</code> tag function.

Notes should permlink that uses appends onto the end of the parent article like <code>#note:2018-08-21_</code>

Need a function in <code>crystalize.rkt</code> that splits out the notes from the document body. And save them to a different table in the SQLite database. And make the <code>note_count</code> column in the <code>articles</code> table accurate.