ohcount: Detector Documentation

# Detector Documentation

## How to Add a New Language

- Add your language to 'src/languages.h' and 'src/hash/languages.gperf'.
- Update 'src/hash/extensions.gperf' to identify files that use the new language (or 'src/hash/filenames.gperf').
- Regenerate the hash header files with 'src/hash/generate_headers'.
- Add your tests to 'test/unit/detector_test.h', rebuild the tests, and run them to confirm the detector changes.
- Follow the detailed instructions in the Parser Documentation.
- Rebuild Ohcount.