update README and Config Type class in configuration

Author: zzzming

README.md

@@ -1,6 +1,6 @@
 # Pulsar AWS S3 sink
 
-Pulsar AWS S3 sink
+Pulsar AWS S3 sink receives JSON messages over Pulsar topics with the same schema and saves them as Parquet format on AWS S3.
 
 ## Operations
 ### Deployment
@@ -11,8 +11,17 @@ GET `admin/v2/functions/connectors` displays the nar is loaded successfully as
 {"name":"aws-s3","description":"AWS S3 sink","sinkClass":"com.kesque.pulsar.sink.s3.AWSS3Sink"}
 ```
 
+`EFFECTIVELY_ONCE` processing guarantees is required since it implements message [cumulative acknowledgement](https://github.com/apache/pulsar/blob/master/pulsar-functions/instance/src/main/java/org/apache/pulsar/functions/source/PulsarSource.java#L129)
+
+Create a sink by uploading a nar file.
+```
+$ bin/pulsar-admin sinks create --archive ./connectors/pulsar-io-s3-1.0.nar --inputs aws-s3-input-topic --name aws-s3-test --sink-config-file ./connectors/pulsar-s3-io.yaml --processing-guarantees EFFECTIVELY_ONCE --subs-position Earliest --sub-name auniquename
+"Created successfully"
 ```
-$ bin/pulsar-admin sinks create --archive ./connectors/pulsar-io-s3-1.0.nar --inputs aws-s3-input-topic --name aws-s3-test --sink-config-file ./connectors/pulsar-s3-io.yaml --processing-guarantees EFFECTIVELY_ONCE --subs-position Earliest
+
+Create a sink from a preloaded nar file.
+```
+$ bin/pulsar-admin sinks create --sink-type aws-s3 --inputs aws-s3-input-topic --name aws-s3-test --sink-config-file ./connectors/pulsar-s3-io.yaml --processing-guarantees EFFECTIVELY_ONCE --subs-position Earliest --subs-name auniquename
 "Created successfully"
 
 $ bin/pulsar-admin sinks list
@@ -24,6 +33,9 @@ $ bin/pulsar-admin sinks delete --name aws-s3-test
 "Deleted successfully"
 ```
 
+### Topic schema registry
+It is mandatory a schema is enforced over the input topics. The Sink would have fatal error to create parquet format when it receives messages with different schemas.
+
 ## Build
 The command to build a nar file.
 ```

s3/src/main/resources/META-INF/services/pulsar-io.yaml

@@ -20,3 +20,4 @@
 name: aws-s3
 description: AWS S3 sink
 sinkClass: com.kesque.pulsar.sink.s3.AWSS3Sink
+sinkConfigClass: com.kesque.pulsar.sink.s3.AWSS3Config