Indexes are listed in ~/.cargo/sources.json and ~/.cargo/local-sources.json, the
former of which is stored in the rust source tree in src/cargo. Each entry in
either of these files is a source, which is a dictionary with (currently) a
single key, "url". The supplied url should point to a json list, each element of
which should be a dictionary with four keys: "name", "uuid", "url", and
"method". The name and uuid serve to identify the package; the method describes
how to fetch the package; the url describes where to fetch it from. Currently
supported methods are "git", "http", and "file".
Signed-off-by: Elly Jones <elly@leptoquark.net>
