Add select integration (#18194)

source/_integrations/select.markdown

@@ -0,0 +1,23 @@
+---
+title: Select
+description: Instructions on how to manage your Select entities with Home Assistant.
+ha_category:
+  - Select
+ha_release: 2021.7
+ha_quality_scale: internal
+ha_domain: select
+ha_codeowners:
+  - '@home-assistant/core'
+---
+
+Keeps track on `select` entities in your environment, their state, and allows
+you to control them. This integration allows other integrations to offer
+a limited set of selectable options for the entity.
+
+### Services
+
+The Number entities registers the following services:
+
+| Service | Data | Description |
+| ------- | ---- | ----------- |
+| `select_option` | `option`<br>`entity_id(s)`<br>`area_id(s)` | Set the current select option of specific `select` entities