Add more description to the OpenUV API key usage docs (home-assistant…

…#8397)

source/_components/openuv.markdown

@@ -35,6 +35,23 @@ component does not automatically query the API for new data after it initially
 loads. To request new data, the `update_data` service may be used.
 </p>
 
+<p class='note warning'>
+Each use of the `update_data` service will consume 1 or 2 API calls, depending
+on which monitored conditions are configured.
+
+If the OpenUV component is configured through the Home Assistant UI (via the
+`Configuration >> Integrations` panel), each service call will consume 2 API
+calls from the daily quota.
+
+If the OpenUV component is configured via `configuration.yaml`, service calls
+will consume 2 API calls if `monitored_conditions` contains both
+`uv_protection_window` and any other condition; any other scenarios will only
+consume 1 API call.
+
+Ensure that you understand these specifications when calling the `update_data`
+service.
+</p>
+
 ## {% linkable_title Configuration %}
 
 To retrieve data from OpenUV, add the following to your `configuration.yaml`