am 964a4121: Merge "[Improve docs for AccountManager] Currently, the docs for AccountManager are somewhat misleading and may cause developer errors. To avoid them, we are properly documenting it." into mnc-dev

* commit '964a41214d19f00e8420500ccaa29e0902933c7e':
  [Improve docs for AccountManager] Currently, the docs for AccountManager are somewhat misleading and may cause developer errors. To avoid them, we are properly documenting it.