message: Use ServiceExt in all examples
diff: @@ -147,8 +147,9 @@ impl ServiceExt for crate::Client {
  /// # #[tokio::main]
  /// # async fn main() -> Result<(), async_nats::Error> {
  /// use futures::StreamExt;
  +/// use async_nats::service::ServiceExt;
  /// let client = async_nats::connect("demo.nats.io").await?;
  -/// let mut service = async_nats::service::add(client, async_nats::service::Config {
  +/// let mut service = client.add_service( async_nats::service::Config {
  /// name: "generator".to_string(),
  /// version: "1.0.0".to_string(),
  /// endpoint: "events.>".to_string(),
  @@ -182,8 +183,9 @@ pub struct Service {
  /// # #[tokio::main]
  /// # async fn main() -> Result<(), async_nats::Error> {
  /// use futures::StreamExt;
  +/// use async_nats::service::ServiceExt;
  /// let client = async_nats::connect("demo.nats.io").await?;
  -/// let mut service = async_nats::service::add(client, async_nats::service::Config {
  +/// let mut service = client.add_service(async_nats::service::Config {
  /// name: "generator".to_string(),
  /// version: "1.0.0".to_string(),
  /// endpoint: "events.>".to_string(),
  @@ -395,8 +397,9 @@ impl Request {
  /// # #[tokio::main]
  /// # async fn main() -> Result<(), async_nats::Error> {
  /// use futures::StreamExt;
  + /// use async_nats::service::ServiceExt;
  /// # let client = async_nats::connect("demo.nats.io").await?;
  - /// # let mut service = async_nats::service::add(client, async_nats::service::Config {
  + /// # let mut service = client.add_service(async_nats::service::Config {
  /// # name: "generator".to_string(),
  /// # version: "1.0.0".to_string(),
  /// # endpoint: "events.>".to_string(),
  