Add a source note to the footer part of the gt table. A source note is
useful for citing the data included in the table. Several can be added to the
footer, simply use multiple calls of
tab_source_note() and they will be
inserted in the order provided. We can use Markdown formatting for the note,
or, if the table is intended for HTML output, we can include HTML formatting.
A table object that is created using the
An object of class