am 38b6d7a1: Merge "docs: Updated In-app Billing docs to support subscriptions for V3." into jb-mr1-dev

# Via Android (Google) Code Review (1) and quddusc (1)
* commit '38b6d7a15c6d5196f9b886f15dc58c28734300da':
  docs: Updated In-app Billing docs to support subscriptions for V3.