Add better installation instructions.
Add better installation instructions.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=239062827

cushon/google-java-format,cushon/google-java-format,sormuras/google-java-format,sormuras/google-java-format,cushon/google-java-format,sormuras/google-java-format