Formats the Caddyfile by adding proper indentation and spaces to improve human readability. It prints the
result to stdout.
If --overwrite is specified, the output will be written to the config file directly instead of printing
it.
If --diff is specified, the output will be compared against the input, and lines will be prefixed with
'-' and '+' where they differ. Note that unchanged lines are prefixed with two spaces for alignment, and
that this is not a valid patch format.
If you wish you use stdin instead of a regular file, use - as the path. When reading from stdin, the
--overwrite flag has no effect: the result is always printed to stdout.