Document the new special support for Optional in AutoValue builders. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=120944222
Document the new special support for Optional in AutoValue builders.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=120944222

eamonnmcmanus/auto,MaTriXy/auto,eamonnmcmanus/auto,google/auto,eamonnmcmanus/auto,MaTriXy/auto,google/auto,google/auto