Refactored mDNS example and added script for example

docs/examples.mDNS.rst

@@ -0,0 +1,64 @@
+mDNS Peer Discovery Example
+==========================
+
+This example demonstrates how to use mDNS (Multicast DNS) for peer discovery in py-libp2p.
+
+Prerequisites
+-------------
+
+First, ensure you have py-libp2p installed and your environment is activated:
+
+.. code-block:: console
+
+    $ python -m pip install libp2p
+
+Running the Example
+-------------------
+
+The mDNS demo script allows you to discover peers on your local network using mDNS. To start a peer, run:
+
+.. code-block:: console
+
+    $ mdns-demo
+
+You should see output similar to:
+
+.. code-block:: console
+
+    Run this from another console to start another peer on a different port:
+    
+    python mdns-demo -p <ANOTHER_PORT>
+    
+    Waiting for mDNS peer discovery events...
+    
+    2025-06-20 23:28:12,052 - libp2p.example.discovery.mdns - INFO - Starting peer Discovery
+
+To discover peers, open another terminal and run the same command with a different port:
+
+.. code-block:: console
+
+    $ python mdns-demo -p 9001
+
+You should see output indicating that a new peer has been discovered:
+
+.. code-block:: console
+
+    Run this from the same folder in another console to start another peer on a different port:
+
+    python mdns-demo -p <ANOTHER_PORT>
+
+    Waiting for mDNS peer discovery events...
+
+    2025-06-20 23:43:43,786 - libp2p.example.discovery.mdns - INFO - Starting peer Discovery
+    2025-06-20 23:43:43,790 - libp2p.example.discovery.mdns - INFO - Discovered: 16Uiu2HAmGxy5NdQEjZWtrYUMrzdp3Syvg7MB2E5Lx8weA9DanYxj
+
+When a new peer is discovered, its peer ID will be printed in the console output.
+
+How it Works
+------------
+
+- Each node advertises itself on the local network using mDNS.
+- When a new peer is discovered, the handler prints its peer ID.
+- This is useful for local peer discovery without requiring a DHT or bootstrap nodes.
+
+You can modify the script to perform additional actions when peers are discovered, such as opening streams or exchanging messages.

docs/examples.rst

@@ -13,3 +13,4 @@ Examples
    examples.pubsub
    examples.circuit_relay
    examples.kademlia
+   examples.mDNS