Update README.md (#1620)
Update README.md (#1620)

update schema link for BaseBall test data to the corresponding json file
linkedin/pinot,fx19880617/pinot-1,linkedin/pinot,fx19880617/pinot-1,apucher/pinot,sajavadi/pinot,apucher/pinot,sajavadi/pinot,fx19880617/pinot-1,fx19880617/pinot-1,linkedin/pinot,linkedin/pinot,linkedin/pinot,fx19880617/pinot-1,sajavadi/pinot,apucher/pinot,sajavadi/pinot,apucher/pinot,sajavadi/pinot,apucher/pinot