Update note formatting help text

[l4mbd0x]

The latest release (rc13) does supports tables but it is not documented over "Formating help" of a note.

and also over the website (presenting for the latter expanded case scenarios of use). Teaching one to become truly more productive by using a markdown based note application (Turtl's premise).

[orthecreedence]

I think the markdown tutorial text might start getting cluttered if we add too many examples.

That said, I think it makes sense to mention what flavor of markdown we support and also any other formats (like TeX math).