markdown-it-hierarchy

Adds numbering hierarchy to markdown-it headers.

const md = require('markdown-it')()
  .use(require('markdown-it-hierarchy'));

Following markdown code:

#  First header of top level
## First subheader of first header
## Second subheader of first header
## Third subheader of first header
#  Second header of top level
#  Third header of top level
## First subheader of third header
### First subheader of first subheader of third header
### Second subheader of first subheader of third header
### Third subheader of first subheader of third header

Will produce hierarchy of headers:

1. First header of top level

1.1. First subheader of first header

1.2. Second subheader of first header

1.3. Third subheader of first header

2. Second header of top level

3. Third header of top level

3.1. First subheader of third header

3.1.1. First subheader of first subheader of third header

3.1.2. Second subheader of first subheader of third header

3.1.3. Third subheader of first subheader of third header