Add country selector (#29242)

* Add country selector

* Add country selector image

source/_docs/blueprint/selectors.markdown

@@ -28,6 +28,7 @@ The following selectors are currently available:
 - [Config entry selector](#config-entry-selector)
 - [Constant selector](#constant-selector)
 - [Conversation agent selector](#conversation-agent-selector)
+- [Country selector](#country-selector)
 - [Date selector](#date-selector)
 - [Date \& time selector](#date--time-selector)
 - [Device selector](#device-selector)
@@ -427,6 +428,32 @@ date:
 The output of this selector will contain the date in Year-Month-Day
 (`YYYY-MM-DD`) format, for example, `2022-02-22`.
 
+## Country selector
+
+The country selector allows a user to pick a country from a list of countries.
+
+![Screenshot of a country selector](/images/blueprints/country_selector.png)
+
+```yaml
+country:
+```
+
+{% configuration entity %}
+countries:
+  description: A list of countries to pick from, this should be ISO 3166 country codes.
+  type: list
+  default: The available countries in the Home Assistant frontend
+  required: false
+no_sort:
+  description: >
+    Should the options be sorted by name, if set to true, the order of the provided countries is kept.
+  type: boolean
+  default: false
+  required: false
+{% endconfiguration %}
+
+The output of this selector is an ISO 3166 country code.
+
 ## Date & time selector
 
 The date selector shows a date and time input that allows the user to specify a