message: docs: improve encrypted field adapter docs
diff: @@ -201,8 +201,31 @@ SQLALCHEMY_CUSTOM_PASSWORD_STORE = None
  # to the DB.
  #
  # Note: the default impl leverages SqlAlchemyUtils' EncryptedType, which defaults
  -# to AES-128 under the covers using the app's SECRET_KEY as key material.
  +# to AesEngine that uses AES-128 under the covers using the app's SECRET_KEY
  +# as key material. Do note that AesEngine allows for queryability over the
  +# encrypted fields.
  #
  +# To change the default engine you need to define your own adapter:
  +#
  +# e.g.:
  +#
  +# class AesGcmEncryptedAdapter( # pylint: disable=too-few-public-methods
  +# AbstractEncryptedFieldAdapter
  +# ):
  +# def create(
  +# self,
  +# app_config: Optional[Dict[str, Any]],
  +# *args: List[Any],
  +# **kwargs: Optional[Dict[str, Any]],
  +# ) -> TypeDecorator:
  +# if app_config:
  +# return EncryptedType(
  +# *args, app_config["SECRET_KEY"], engine=AesGcmEngine, **kwargs
  +# )
  +# raise Exception("Missing app_config kwarg")
  +#
  +#
  +# SQLALCHEMY_ENCRYPTED_FIELD_TYPE_ADAPTER = AesGcmEncryptedAdapter
  SQLALCHEMY_ENCRYPTED_FIELD_TYPE_ADAPTER = ( # pylint: disable=invalid-name
  SQLAlchemyUtilsAdapter
  )
  