Clarify debug URL parameter behavior in documentation

Updated the explanation of the debug URL parameter behavior to clarify that it stays active in session storage until the tab or window is closed.

Author: maxmilhan

src/connections/auto-instrumentation/web-setup.md

@@ -219,7 +219,7 @@ User activity is not collected by default after SDK installation. To collect act
 ```
 https://my-website.com?segment_signals_debug=true
 ```
-Loading the site with this debug URL parameter saves a cookie onto that device that sends activities and expires in 24 hours. The URL parameter does not need to be present on each page load.
+Loading the site with this debug URL parameter stays active in session storage until the tab or window is closed. Within a session the URL parameter does not need to be present on each page load.
 
 You can _turn off debugging_ by doing: