Use named kwarg for add_entities' update_before_add parameter (#1695)

Author: rytilahti

docs/creating_platform_code_review.md

@@ -69,7 +69,7 @@ PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
     ```
 
 2. Avoid passing in `hass` as a parameter to the entity. `hass` will be set on the entity when the entity is added to Home Assistant. This means you can access `hass` as `self.hass` inside the entity.
-3. Do not call `update()` in constructor, use `add_entities(devices, True)` instead.
+3. Do not call `update()` in constructor, use `add_entities(devices, update_before_add=True)` instead.
 4. Do not do any I/O inside properties. Cache values inside `update()` instead.
 5. When dealing with time, state and/or attributes should not contain relative time since something happened. Instead, it should store UTC timestamps.
 6. Leverage the [entity lifecycle callbacks](core/entity.md#lifecycle-hooks) to attach event listeners or clean up connections.

docs/integration_fetching_data.md

@@ -148,7 +148,7 @@ Some APIs will offer an endpoint per device. It sometimes won't be possible to m
 
 If you can map exactly one device endpoint to a single entity, you can fetch the data for this entity inside the `update()`/`async_update()` methods. Make sure polling is set to `True` and Home Assistant will call this method regularly.
 
-If your entities need to fetch data before being written to Home Assistant for the first time, pass `True` to the `add_entities` method: `add_entities([MyEntity()], True)`.
+If your entities need to fetch data before being written to Home Assistant for the first time, pass `update_before_add=True` to the `add_entities` method: `add_entities([MyEntity()], update_before_add=True)`.
 
 You can control the polling interval for your integration by defining a `SCAN_INTERVAL` constant in your platform. Careful with setting this too low. It will take up resources in Home Assistant, can overwhelm the device hosting the API or can get you blocked from cloud APIs. The minimum allowed value is 5 seconds.