docs: update README to add run_funnel_report tool

Author: cagnusmarlsen

README.md

@@ -36,6 +36,7 @@ to provide several
 ### Run core reports 📙
 
 - `run_report`: Runs a Google Analytics report using the Data API.
+- `run_funnel_report`: Runs a Google Analytics funnel report using the Data API.
 - `get_custom_dimensions_and_metrics`: Retrieves the custom dimensions and
   metrics for a specific property.