docs(examples/readme): fix broken link

Related: #3536.

Pull-Request: #4984.

Author: trueNAHO

examples/README.md

@@ -20,6 +20,6 @@ A set of examples showcasing how to use rust-libp2p.
 
 - [IPFS Private](./ipfs-private) Implementation using the gossipsub, ping and identify protocols to implement the ipfs private swarms feature.
 
-- [Ping](./ping) Small `ping` clone, sending a ping to a peer, expecting a pong as a response. See [tutorial](../src/tutorials/ping.rs) for a step-by-step guide building the example.
+- [Ping](./ping) Small `ping` clone, sending a ping to a peer, expecting a pong as a response. See [tutorial](../libp2p/src/tutorials/ping.rs) for a step-by-step guide building the example.
 
 - [Rendezvous](./rendezvous) Rendezvous Protocol. See [specs](https://github.com/libp2p/specs/blob/master/rendezvous/README.md).