docs: include dependencies in sample README

.github/release-please.yml

@@ -2,4 +2,4 @@ primaryBranch: postgresql-dialect
 releaseType: java-yoshi
 bumpMinorPreMajor: true
 handleGHRelease: true
-extraFiles: ["README.md"]
+extraFiles: ["README.md", "samples/java/jdbc/README.md"]

samples/java/jdbc/README.md

@@ -4,6 +4,69 @@ This sample application shows how to connect to Cloud Spanner through PGAdapter
 `JDBC` PostgreSQL driver. PGAdapter is automatically started in-process together with the sample
 application.
 
+### Dependencies
+
+The sample application adds the following dependencies:
+
+<!--- {x-version-update-start:google-cloud-spanner-pgadapter:released} -->
+```xml
+<!-- [START pgadapter_and_jdbc_dependency] -->
+<dependency>
+  <groupId>org.postgresql</groupId>
+  <artifactId>postgresql</artifactId>
+  <version>42.6.0</version>
+</dependency>
+<dependency>
+  <groupId>com.google.cloud</groupId>
+  <artifactId>google-cloud-spanner-pgadapter</artifactId>
+  <version>0.23.0</version>
+</dependency>
+<!-- [END pgadapter_and_jdbc_dependency] -->
+```
+<!--- {x-version-update-end} -->
+
+### Connecting
+PGAdapter is started in-process with the sample application:
+
+```java
+<!-- [START pgadapter_start_in_process] -->
+OptionsMetadata.Builder builder =
+    OptionsMetadata.newBuilder()
+        .setProject(project)
+        .setInstance(instance)
+        // Start PGAdapter on any available port.
+        .setPort(0);
+ProxyServer server = new ProxyServer(builder.build());
+server.startServer();
+server.awaitRunning();
+<!-- [END pgadapter_start_in_process] -->
+```
+
+The PostgreSQL JDBC driver can connect to the in-process PGAdapter instance. This example uses
+Unix Domain Sockets for the lowest possible latency:
+
+```java
+<!-- [START pgadapter_connect_in_process] -->
+// Create a connection URL that will use Unix domain sockets to connect to PGAdapter.
+String connectionUrl =
+  String.format(
+      "jdbc:postgresql://localhost/%s?"
+          + "socketFactory=org.newsclub.net.unix.AFUNIXSocketFactory$FactoryArg"
+          + "&socketFactoryArg=/tmp/.s.PGSQL.%d",
+      database, server.getLocalPort());
+try (Connection connection = DriverManager.getConnection(connectionUrl)) {
+  try (ResultSet resultSet = 
+      connection.createStatement().executeQuery("select 'Hello World!' as greeting")) {
+    while (resultSet.next()) {
+      System.out.printf("\nGreeting: %s\n\n", resultSet.getString("greeting"));
+    }
+  }
+}
+<!-- [END pgadapter_connect_in_process] -->
+```
+
+### Run Sample
+
 Run the sample with the following command:
 
 ```shell