Source Google Analytics: update migration guide (#30989)

docs/integrations/sources/google-analytics-data-api-migrations.md

@@ -3,4 +3,25 @@
 ## Upgrading to 2.0.0
 
 A major update of most streams to avoid having duplicate stream names. This is relevant for the connections having more than one property ID.
-Resetting a connector is needed if you have more than one property ID in your config.
+Resetting a connector is needed if you have more than one property ID in your config.
+
+Let's say you have three property IDs - `0001`, `0002`, `0003`. Two of them will be included in the stream names:
+ - "daily_active_users",
+ - "daily_active_users_property_0002",
+ - "daily_active_users_property_0003",
+ - "weekly_active_users",
+ - "weekly_active_users_property_0002"
+ - "weekly_active_users_property_0003"
+...
+
+If the number of properties in your config does not exceed one, you will not see changes to your stream names, and the reset is not required:
+ - "daily_active_users",
+ - "weekly_active_users"
+
+Once you add the second property ID, new streams will have names with the new property ID included. Existing streams will not be affected:
+ - "daily_active_users",
+ - "daily_active_users_property_0002",
+ - "weekly_active_users",
+ - "weekly_active_users_property_0002"
+
+If you add the second+ property after running the upgrade, the reset is not required.