Minimal URI confusion (in README)

[justin2004]

In the README there is:

A minimal URI that uses only the resource locator is also possible.

x-sparql-anything ':' URL

and there is an example that uses that scheme with https:// but for completeness it would help to have a file:// example right by it.

Without that it is natural for users to want to try:

SERVICE <x-sparql-anything:/some/path/examples/example1.json>

and get an ERROR:

No match available

While this does work:

SERVICE <x-sparql-anything:file:///some/path/examples/example1.json>