Default sectioning

If the sectioning part is empty, it is possible to use a default sectioning part defined in the meta-data block using the sectioning-levels key:

---
pandoc-numbering:
  ex:
    general:
      sectioning-levels: -.+.
---
Section
=======

Subsection
----------

Exercise #ex:

will be rendered as

Section
=======

Subsection
----------

[**Exercise 1.1**]{#ex:1.1.1 .pandoc-numbering-text .ex}

You can also use the first-section-level and last-section-level key (first section level to appear, last section level to appear):

---
pandoc-numbering:
  ex:
    general:
      sectioning-levels: -.+.
---

is equivalent to

---
pandoc-numbering:
  ex:
    general:
      first-section-level: 2
      last-section-level: 2
---