doc: update README.md to notice the user about RisingWave's usage of Scarf (#17012)

Co-authored-by: hengm3467 <[email protected]>

Author: alicelyy

README.md

@@ -71,6 +71,9 @@ Then follow the prompts to start and connect to RisingWave.
 
 To learn about other installation options, such as using a Docker image, see [Quick Start](https://docs.risingwave.com/docs/current/get-started/).
 
+> Please note: RisingWave uses [Scarf](https://scarf.sh/) to collect anonymized installation analytics. These analytics help support us understand and improve the distribution of our package. 
+> The privacy policy of Scarf is available at [https://about.scarf.sh/privacy-policy](https://about.scarf.sh/privacy-policy).
+
 ## Production deployments
 
 [**RisingWave Cloud**](https://cloud.risingwave.com) offers the easiest way to run RisingWave in production, with a _forever-free_ developer tier.