Public/Private dir mapping

[mturoci]

Currently, our docs say

-public-dir value
        additional directory to serve files from, in the format "[url-path]:[filesystem-path]", e.g. "/public/files/:/some/local/path" will host /some/local/path/foo.txt at /public/files/foo.txt; multiple directory mappings allowed

and uses : as separator between remove/local. However, in code we split on @.

What should be the correct separator so that I know whether to fix code or docs @lo5? I assume docs :)

TODO: Add a note about case when running wave server via wave run - the path is not relative to where wave run is called from, but to where it the server is located, which should be venv so each path needs to start with ../ to move up from venv and get into project root.