Corrected small typo in README.
Corrected small typo in README.

PiperOrigin-RevId: 240358447

google-research/google-research,google-research/google-research,google-research/google-research,google-research/google-research,google-research/google-research,google-research/google-research,google-research/google-research,google-research/google-research,google-research/google-research,google-research/google-research,google-research/google-research