Add comments to examples/ping_pong_bot

examples/ping_pong_bot/src/main.rs

@@ -2,12 +2,18 @@ use teloxide::prelude::*;
 
 #[tokio::main]
 async fn main() {
+    // Configure a fancy logger. Let this bot print everything, but restrict
+    // teloxide to only log errors.
     std::env::set_var("RUST_LOG", "ping_pong_bot=trace");
     std::env::set_var("RUST_LOG", "teloxide=error");
     pretty_env_logger::init();
     log::info!("Starting the ping-pong bot!");
 
+    // Creates a dispatcher of updates with the specified bot. Don't forget to
+    // replace `MyAwesomeToken` with yours.
     Dispatcher::<RequestError>::new(Bot::new("MyAwesomeToken"))
+        // Registers a message handler. Inside a body of the closure, answer
+        // `"pong"` to an incoming message.
         .message_handler(&|ctx: DispatcherHandlerCtx<Message>| async move {
             ctx.answer("pong").send().await?;
             Ok(())