docs(kafka): add example for ingestion from confluent cloud (#3789)

metadata-ingestion/source_docs/kafka.md

@@ -33,6 +33,30 @@ sink:
   # sink configs
 ```
 
+### Connecting to Confluent Cloud
+
+If using Confluent Cloud you can use a recipe like this. In this `consumer_config.sasl.username` and `consumer_config.sasl.password` are the API credentials that you get (in the Confluent UI) from your cluster -> Data Integration -> API Keys. `schema_registry_config.basic.auth.user.info`  has API credentials for Confluent schema registry which you get (in Confluent UI) from Schema Registry -> API credentials.
+
+```yml
+source:
+  type: "kafka"
+  config:
+    connection:
+      bootstrap: "abc-defg.eu-west-1.aws.confluent.cloud:9092"
+      consumer_config:
+        security.protocol: "SASL_SSL"
+        sasl.mechanism: "PLAIN"
+        sasl.username: "CLUSTER_API_KEY_ID"
+        sasl.password: "CLUSTER_API_KEY_SECRET"
+      schema_registry_url: "https://abc-defgh.us-east-2.aws.confluent.cloud"
+      schema_registry_config:
+        basic.auth.user.info: "REGISTRY_API_KEY_ID:REGISTRY_API_KEY_SECRET"
+
+sink:
+  # sink configs
+```
+
+
 ## Config details
 
 Note that a `.` is used to denote nested fields in the YAML recipe.