Add Local calendar integration documentation (#24429)

Co-authored-by: Franck Nijhof <frenck@frenck.nl>

source/_integrations/local_calendar.markdown

@@ -0,0 +1,31 @@
+---
+title: Local Calendar
+description: Instructions on how to use Local Calendars in Home Assistant.
+ha_category:
+  - Calendar
+ha_iot_class: Local Polling
+ha_release: 2022.12
+ha_config_flow: true
+ha_domain: local_calendar
+ha_platforms:
+  - calendar
+ha_codeowners:
+  - '@allenporter'
+ha_integration_type: integration
+---
+
+The local calendar integration allows you to create a calendar of events in Home Assistant for powering automations.
+
+A calendar entity has a state and attributes that represent the next upcoming event (only). A calendar trigger is a much more flexible way to power automations with fewer limitations than using the entity state.
+
+{% include integrations/config_flow.md %}
+
+## Calendar Event Automations
+
+Individual Calendar *Events* are what powers automations such as:
+
+* Turn on a light at the *start* of the event named *Front Yard Light*
+* Send a notification *5 minutes before the start of any event*
+* Stop the media player *30 minutes after* the *end* of the event named *Exercise*.
+
+See [Calendar Automations](/integrations/calendar#automation) for an overview, and read more about [Calendar Trigger Variables](/docs/automation/templating/#calendar) for the available information you can use in a condition or action such as the event `summary`, `description`, `location` and more.