[Request] Consider Headings

[benboeck]

Hello,
thank you for this plugin, the mind map looks great!
I have a request: would it be possible to consider headings?
For example:

Heading1

Heading2

Heading3

Some text
...
should look like:

Heading 1 --- Heading 2 --- Heading 3
                            Some text

[vipzhicheng]

This is also a feature that I need, but in the upstream repo, the mark map renderer seems not supported.