docs: remove duplicated title (backport release-3.1.x) (#15625)

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

docs/sources/get-started/quick-start.md

@@ -349,7 +349,6 @@ You have completed the Loki Quickstart demo. So where to go next?
 Head back to where you started from to continue with the Loki documentation: [Loki documentation](https://grafana.com/docs/loki/latest/get-started/quick-start/).
 {{< /docs/ignore >}}
 
-## Complete metrics, logs, traces, and profiling example
 If you would like to run a demonstration environment that includes Mimir, Loki, Tempo, and Grafana, you can use [Introduction to Metrics, Logs, Traces, and Profiling in Grafana](https://github.com/grafana/intro-to-mlt).
 It's a self-contained environment for learning about Mimir, Loki, Tempo, and Grafana.