doc/tutorial.md walks from probe detection to JEDEC ID over EXTEST and
forward-references the BSCAN proxy path. Includes:
- prerequisites and build/launch
- chain scan, FPGA identification, registry lookup
- IR/DR primitive sanity check via the IDCODE register
- SPI JEDEC ID over EXTEST (with the speed caveat)
- recipe to add a new FPGA target
- troubleshooting cheat sheet
README and CLAUDE.md updated to point at it.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
