- A (level 1,size=none)
## B (level 2->1,size=2)
- C (level 1->5,size=none)
- D (level 1->5,size=none)
- E (level 5->9,size=none)
- F (level 1->5,size=none)
### G (level 3->1,size=3)
- H (level 5,size=none)
- I (level 1,size=none)
support syntax like - ### title level=1 and size=3
sort headings‘ levels
support syntax like
- ### title
level=1 and size=3