Fixed file path for serving classify.html over SimpleHTTPServer

When using `classify KLASS --html --serve --port <port>` classify writes the documentation for `KLASS` to `/current/directory/output/classify.html`. However, it attempts to serve the documentation from `/current/directory/classify.html`. I have made a simple change so it serves the correct file.

For future reference, perhaps `classify` should write the documentation to a folder with a less generic name than output.