For some documents, we may want a terse or deeper TOC depth. For
example, short documents may want just the level-0 in the TOC, while
longer documents may want depth 1 or 2, or even deeper; also, some
documents may not use the document-title levels [0], only section
levels [1], and so may want to increase the TOC depth.
Additionally, allow per-format depth. For example, split-html has a
single page dedicated to the TOC, so there we may want a deeper TOC,
while on the html output, where the TOC is on the same page as the
whole document, a shorter TOC is preferred.
[0] https://docs.asciidoctor.org/asciidoc/latest/syntax-quick-reference/#document-header
[1] https://docs.asciidoctor.org/asciidoc/latest/syntax-quick-reference/#section-titles
Signed-off-by: Yann E. MORIN <yann.morin@orange.com>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
