Add documentation for the HKO integration (#28608)

source/_integrations/hko.markdown

@@ -0,0 +1,25 @@
+---
+title: Hong Kong Observatory
+description: Instructions on how to integrate the Hong Kong Observatory (HKO) Open Data API into Home Assistant.
+ha_category:
+  - Weather
+ha_release: 2024.2
+ha_iot_class: Cloud Polling
+ha_config_flow: true
+ha_codeowners:
+  - '@MisterCommand'
+ha_domain: hko
+ha_platforms:
+  - weather
+ha_integration_type: integration
+---
+
+The HKO integration retrieves weather data from the [Hong Kong Observatory](https://www.hko.gov.hk/tc/index.html) [Open Data API](https://www.hko.gov.hk/en/abouthko/opendata_intro.htm) for meteorological data in HKSAR.
+
+There is currently support for the following platforms within Home Assistant:
+
+- [Weather](#weather-platform)
+
+It displays the weather of your selected location and the 5-day weather forecast for Hong Kong.
+
+{% include integrations/config_flow.md %}