Update README.md

Co-authored-by: dtjones404 <[email protected]>

README.md

@@ -95,7 +95,7 @@ Attach a method which is called and will attach values to **each metric's dimens
 
 ```javascript
 $logger.addMetricDimensionBuilder(() => ({
-  token_use: true,
+  token_used: true,
   type: "user_id_token",
 }));
 ```