Enhancement: Kademlia example: bind all interfaces and show public IP

@sumanjeet0012 is already working on this.

Since Aug 12, 2025.

### Description

There are two connectivity issues in the Kademlia DHT example at:
- examples/kademlia/kademlia.py: https://github.com/libp2p/py-libp2p/blob/main/examples/kademlia/kademlia.py

1) The example binds to 127.0.0.1, which prevents external peers from connecting (e.g., on AWS EC2). Binding to 0.0.0.0 resolves this by listening on all interfaces.

2) The example logs/advertises the node’s address using 127.0.0.1, which is incorrect for remote peers. It should display a routable/public IP so that the printed bootstrap command is usable.

Example of incorrect log output in docs:
- https://github.com/libp2p/py-libp2p/blob/main/docs/examples.kademlia.rst

### Motivation

- On cloud hosts and remote deployments, binding to localhost (127.0.0.1) prevents other nodes from connecting to the example node.
- Logging a bootstrap multiaddr with 127.0.0.1 misleads users and results in failed connection attempts from remote peers.
- Fixing both issues improves the out-of-the-box experience and mirrors real-world usage patterns.

### Current Implementation

- The example sets:
- listen address: `/ip4/127.0.0.1/tcp/{port}`
- advertised/logged address: `/ip4/127.0.0.1/tcp/{port}/p2p/{peer_id}`

- Result:
- Other nodes cannot connect when the example runs on a remote host.
- Documentation/logs show a non-routable address for bootstrapping.

### Are you planning to do it yourself in a pull request ?

Maybe