No way to create fixture for a top-level .md without a parent dir

[holyjak]

(After #3 merged) If we have resources/MySpec.md and resources is the root on the classpath then there is no way to match a fixture to it because a fixture must be inside a namespace and thus will have the name <ns>.<fixture name>.

Solutions: Perhaps best is to just document it and require there is an extra top level dir, e.g. resources/specifications/MySpec.md.