Add date platform docs (#24986)

Co-authored-by: Franck Nijhof <frenck@frenck.nl>
Co-authored-by: Philip Allgaier <philip.allgaier@gmx.de>

source/_integrations/date.markdown

@@ -0,0 +1,31 @@
+---
+title: Date
+description: Instructions on how to set up date entities within Home Assistant.
+ha_category:
+  - Date
+ha_release: '2023.6'
+ha_domain: date
+ha_quality_scale: internal
+ha_codeowners:
+  - '@home-assistant/core'
+ha_integration_type: entity
+---
+
+The Date integration is built for the controlling and monitoring of dates on devices.
+
+Date entities cannot be created manually, but can be provided by other integrations. If you are looking for a way to create a similar entity, please take a look at the [Date/Time helper](/integrations/input_datetime).
+
+## Services
+
+### date services
+
+Available services: `date.set_value`
+
+### Service `date.set_value`
+
+Set a new value for the date entity.
+
+| Service data attribute | Optional | Description |
+| ---------------------- | -------- | ----------- |
+| `entity_id` | no | String or list of strings that point at `entity_id`'s of dates to control.
+| `date` | no | New date value to set.