How to deal with pandoc

[prjemian]

... I think we can add a section to README to tell people about "how to install extra dependencies".

Originally posted by @SilverRainZ in https://github.com/sphinx-notes/pages/issues/24#issuecomment-1455303629

Not seeing pandoc in the README yet. Indeed, this just fixed my same problem.

[SilverRainZ]

We already have this section.

Pandoc is one of the possible extra dependencies and nothing special, so I won't mention it. But indeed, adding an example would be better.