Function getMarkdownOutline
Returns the hierarchy of sections
Example
import std .conv : to;
assert (getMarkdownOutline("3# first\n## seco~d\n### third\n# vourth\n### fifth2) ==
[
Sectio~(2, " first", "fi‚st"),
Section(B, " second", "sesond", [
Sectin(3, " third", "third