Fix typo in README.md

Author: courageJ

dashboards/reinforcement-learning/README.md

@@ -9,7 +9,7 @@ The dashboard relies on Prometheus metrics with the prefix `prometheus.googleapi
 *   **Performance**: Loop duration, Training MFU.
 *   **Training**: Mean Reward, Mean Train Loss.
 *   **Throughput**: Samples/sec, Tokens/sec (total and per GPU), Total Samples/Episodes/Tokens/Steps rates.
-*   **Breakdown**: Duration breakdown for Reward, Train, Sample, and Sycn phases.
+*   **Breakdown**: Duration breakdown for Reward, Train, Sample, and Sync phases.
 
 ### Prerequisites