Fix typo in friendly_name attribute explanation (#2851)

Author: eifinger

docs/core/entity.md

@@ -145,7 +145,7 @@ The entity's name property only identifies the data point represented by the ent
 If the entity represents a single main feature of a device the entity should typically have its name property return `None`.
 The "main feature" of a device would for example be the `LightEntity` of a smart light bulb.
 
-The `friendly_name` state attribute is generated by combining then entity name with the device name as follows:
+The `friendly_name` state attribute is generated by combining the entity name with the device name as follows:
 - The entity is not a member of a device: `friendly_name = entity.name`
 - The entity is a member of a device and `entity.name` is not `None`: `friendly_name = f"{device.name} {entity.name}"`
 - The entity is a member of a device and `entity.name` is `None`: `friendly_name = f"{device.name}"`