docs: min instead of max in attempts made or truncate in custom backo…

…ff (#2830)

docs/gitbook/bull/patterns/custom-backoff-strategy.md

@@ -46,7 +46,7 @@ const myQueue = new Queue("Server B", {
         console.error({ attemptsMade, err, options });
         return Math.round(
           Math.random() *
-            (Math.pow(2, Math.max(attemptsMade, truncate)) - 1) *
+            (Math.pow(2, Math.min(attemptsMade, truncate)) - 1) *
             delay
         );
       },