docs: Add maven central link. (#100)

* update

* Update .readme-partials.yaml

Co-authored-by: Tianzi Cai <tianzi@google.com>

Co-authored-by: Tianzi Cai <tianzi@google.com>

.readme-partials.yaml

@@ -16,8 +16,7 @@ custom_content: |
 
   ## Downloading and Using the Connector
 
-  <!--- TODO(jiangmichael): Release on Maven Central and add Maven Central link -->
-    The connector will be available from the Maven Central repository. It can be used using the `--packages` option or the `spark.jars.packages` configuration property.
+    The connector is available from the [Maven Central repository](https://search.maven.org/artifact/com.google.cloud/pubsublite-spark-sql-streaming). You can download and pass it in the `--packages` option when using the `spark-submit` command or set it via the `spark.jars.packages` [configuration property](https://spark.apache.org/docs/latest/configuration.html#available-properties).
 
   ## Compatibility
   | Connector version | Spark version |