[KYUUBI #6870][FOLLOWUP] Correct file name of grafana/README.md

### Why are the changes needed?

Fix a typo of file name.

### How was this patch tested?

Review.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #7074 from pan3793/6870-f.

Closes #6870

45915d9 [Cheng Pan] [KYUUBI #6870][FOLLOWUP] Correct file name of grafana/README.md

Authored-by: Cheng Pan <[email protected]>
Signed-off-by: Cheng Pan <[email protected]>

Author: pan3793

grafana/REAMDE.md renamed to grafana/README.md

@@ -9,7 +9,7 @@ By default, Kyuubi server enables metrics system and exposes Prometheus endpoint
 to use the Kyuubi Grafana Dashboard, you are supposed to have an available Prometheus and Grafana service, then
 configure Prometheus to scrape Kyuubi metrics, add the Prometheus data source into Grafana, and then import the
 `dashboard-template.json` into Grafana and customize. For more details, please read the
-[Kyuubi Docs](https://kyuubi.readthedocs.io/en/master/monitor/metrics.html#grafana-and-prometheus) 
+[Kyuubi Docs](https://kyuubi.readthedocs.io/en/master/monitor/metrics.html#grafana-and-prometheus)
 
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