Document translation of entity names (#1707)

* Document translation of entity names

* Adjust according to changes in the implementation

* Update docs/internationalization/core.md

Co-authored-by: Martin Hjelmare <[email protected]>

* Update core.md

---------

Co-authored-by: Martin Hjelmare <[email protected]>

Author: emontnemery

docs/internationalization/core.md

@@ -149,6 +149,23 @@ The translation strings for repairs issues are defined under the `issues` key. A
 
 ### Entities
 
+#### Name of entities
+Integrations can provide translations for names of its entities. To do this, provide an `entity` object, that contains translations of the names and set the entity's `translation_key` property to a key under a domain in the `entity` object.
+If the entity's `translation_key` property is not `None` and the `entity` object provides a translated name, `EntityDescription.name` will be ignored.
+
+The following example `strings.json` is for a `sensor` entity with its `translation_key` property set to `thermostat_mode`:
+```json
+{
+  "entity": {
+    "sensor": {
+      "thermostat_mode": {
+        "name": "Thermostat mode"
+      }
+    }
+  }
+}
+```
+
 #### State of entities
 
 Integrations can provide translations for states of its entities under other integrations like sensor if the base entity component does not provide translations, or if the translation provided by the base entity component do not match the integration's entity. To do this, provide an `entity` object, that contains translations for states and set the entity's `translation_key` property to a key under a domain in the `entity` object.