Use edown for documentation generation.

README.md

doc/README.md

doc/edoc-info

doc/onion_base16.md

doc/onion_base32.md

doc/onion_base64.md

doc/onion_binary.md

doc/onion_cell.md

doc/onion_certs_cell.md

doc/onion_config.md

doc/onion_curve25519.md

doc/onion_descriptor.md

doc/onion_dh.md

doc/onion_document.md

doc/onion_ed25519.md

doc/onion_file.md

doc/onion_lists.md

doc/onion_os.md

doc/onion_pem.md

doc/onion_protocol.md