fix: correct heading formatting in mDNS example documentation

sumanjeet0012 · sumanjeet0012 · commit 555e38910953 · 2025-06-24T14:25:42.000+05:30
diff --git a/docs/examples.mDNS.rst b/docs/examples.mDNS.rst
@@ -1,5 +1,5 @@
 mDNS Peer Discovery Example
-==========================
+===========================
 
 This example demonstrates how to use mDNS (Multicast DNS) for peer discovery in py-libp2p.
 
