feat: add disposable-token example for docs

examples/token/src/main/java/momento/client/example/docs_examples/DocExamplesJavaAPIs.java

@@ -0,0 +1,33 @@
+package momento.client.example.docs_examples;
+
+import momento.sdk.AuthClient;
+import momento.sdk.auth.CredentialProvider;
+import momento.sdk.auth.accessControl.DisposableTokenScopes;
+import momento.sdk.auth.accessControl.ExpiresIn;
+import momento.sdk.responses.auth.GenerateDisposableTokenResponse;
+
+public class DocExamplesJavaAPIs {
+
+  public static void example_API_GenerateDisposableToken(AuthClient authClient) {
+    final GenerateDisposableTokenResponse response =
+        authClient
+            .generateDisposableTokenAsync(
+                DisposableTokenScopes.cacheKeyReadWrite("squirrel", "mo"), ExpiresIn.minutes(30))
+            .join();
+    if (response instanceof GenerateDisposableTokenResponse.Success success) {
+      System.out.println("Successfully generated the disposable token: " + success.authToken());
+    } else if (response instanceof GenerateDisposableTokenResponse.Error error) {
+      throw new RuntimeException(
+          "An error occurred while attempting to generate disposable token: "
+              + error.getErrorCode(),
+          error);
+    }
+  }
+
+  public static void main(String[] args) {
+    try (final AuthClient authClient =
+        AuthClient.builder(CredentialProvider.fromEnvVar("MOMENTO_API_KEY")).build()) {
+      example_API_GenerateDisposableToken(authClient);
+    }
+  }
+}