> The idea here is to let user take notes in mark down, then with one click convert it to mind map to make a structure to the text.

An interesting idea, although a bit counter-intuitive: in principle, a mind map helps you to visualize ideas better, in a way that lets you restructure them, etc. This visual outlining process is a tool, not the end goal. You'd expect to start with a rough diagram of idea nodes, not with a list. That said, starting with text could be useful in some cases.