Add Fluent Bit retry configuration

By default Fluent Bit [uses](https://docs.fluentbit.io/manual/administration/scheduling-and-retries#configuring-retries) a Retry_Limit of 1.
Since senders want to ensure that telemetry data is ingested, even if the observability backend (e.g. SAP Cloud Logging) is temporarily unavailable (e.g. due to network problems), we should recommend at least 3 retries.

docs/ingest-via-json-api-endpoint-3416f8f.md

@@ -23,7 +23,8 @@ You can use arbitrary log shippers to send to the mTLS ingest JSON API endpoint.
     tls true
     Compress gzip
     URI /
-   Format json
+    Format json
+    Retry_Limit 3
 
 ```