Update README.md

reflow card prose (no hard-wrap) + patch modality-presence overclaims (responses/protocol/vectors)

card: per-row pcap-modality + Solana-benigns asymmetry + count/citation fixes

fix How-to-use: snapshot_download (load_dataset incompatible with tree-shaped bundles)

initial release: 31 curated bundles (2026-05-13)

initial commit