map-url = "http://from.here/ http://some.where/"
adds a single mapping for the left side URL to the given destination.
If you append an asterisk '*' to the left side URL, it is prefix
matched against the incoming URL. Whenever that prefix matches, the URL
will be replaced completely by the right side. If you additionally
append an asterisk to the right side URL, the part of incoming URL coming after
the prefix, will be appended to the right side URL. Thus, for a line :
map-url = "http://source/* http://destination/*"
and an incoming URL of "http://source/some/path", the result will be
"http://destination/some/path".