Add google-symptoms data dip message (#1537)

* add dip warning to top of page

* mark as NOT inactive

* use html italics

Author: nmdefries

docs/api/covidcast-signals/google-symptoms.md

@@ -1,7 +1,7 @@
 ---
-title: <i>inactive</i> Google Search Trends Symptoms
+title: Google Search Trends Symptoms
 parent: Data Sources and Signals
-nav_order: 2
+nav_order: 1
 grand_parent: Main Endpoint (COVIDcast)
 ---
 
@@ -16,6 +16,8 @@ grand_parent: Main Endpoint (COVIDcast)
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** To download or use the data, you must agree to the Google [Terms of Service](https://policies.google.com/terms)
 
+<div style="background-color:#ff00001c; padding: 10px 30px;"><strong>Data issue:</strong> Between May 13 2024 and August 6 2024, signals values were 25%-50% lower compared to previous time periods. This affects <i>all</i> signals and symptom sets. Currently there is no explanation for the decrease in search volume, and the issue is under investigation by our data source partners.</div>
+
 ## Overview
 
 This data source is based on the [COVID-19 Search Trends symptoms