fix java resource sampling example (#30553)

Author: cecile75

content/en/tracing/trace_pipeline/ingestion_mechanisms.md

@@ -90,7 +90,7 @@ For example, to capture 100% of traces for the resource `GET /checkout` from the
 
 ```
 # using system property
-java -Ddd.trace.sampling.rules='[{\"service\": \"my-service\", \"resource\": \"GET /checkout\", \"sample_rate\":1},{\"service\": \"my-service\", \"sample_rate\":0.2}]' -javaagent:dd-java-agent.jar -jar my-app.jar
+java -Ddd.trace.sampling.rules='[{"service": "my-service", "resource": "GET /checkout", "sample_rate":1},{"service": "my-service", "sample_rate":0.2}]' -javaagent:dd-java-agent.jar -jar my-app.jar
 
 # using environment variables
 export DD_TRACE_SAMPLING_RULES='[{"service": "my-service", "resource":"GET /checkout", "sample_rate": 1},{"service": "my-service", "sample_rate": 0.2}]'