doc: dns example (#75)

```console
Libp2p/py-multiaddr-fork$ python examples/dns/trio_dns_examples.py 
DNS Resolution Examples with Trio
==================================================
=== Basic DNS Resolution with Trio ===
Original address: /dns/example.com
Protocols: ['dns']
Resolved to 12 addresses:
  1. /ip4/23.192.228.84
  2. /ip4/23.215.0.136
  3. /ip4/23.215.0.138
  4. /ip4/96.7.128.175
  5. /ip4/96.7.128.198
  6. /ip4/23.192.228.80
  7. /ip6/2600:1406:bc00:53::b81e:94c8
  8. /ip6/2600:1406:bc00:53::b81e:94ce
  9. /ip6/2600:1408:ec00:36::1736:7f24
  10. /ip6/2600:1408:ec00:36::1736:7f31
  11. /ip6/2600:1406:3a00:21::173e:2e65
  12. /ip6/2600:1406:3a00:21::173e:2e66

=== Bootstrap Node Resolution with Trio ===

Resolving: /dnsaddr/github.com/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
  Peer ID: QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
  Resolved to 1 addresses:
    1. /ip4/140.82.121.3/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN

Resolving: /dnsaddr/cloudflare.com/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
  Peer ID: QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
  Resolved to 1 addresses:
    1. /ip4/104.16.132.229/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN

Resolving: /dnsaddr/google.com/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
  Peer ID: QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
  Resolved to 1 addresses:
    1. /ip4/142.250.184.206/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN

=== DNS Protocol Comparison with Trio ===

Testing DNS (both IPv4 and IPv6): /dns/example.com
  Resolved to 12 addresses:
    1. /ip4/23.215.0.138
    2. /ip4/96.7.128.175
    3. /ip4/96.7.128.198
    4. /ip4/23.192.228.80
    5. /ip4/23.192.228.84
    6. /ip4/23.215.0.136
    7. /ip6/2600:1406:bc00:53::b81e:94ce
    8. /ip6/2600:1408:ec00:36::1736:7f24
    9. /ip6/2600:1408:ec00:36::1736:7f31
    10. /ip6/2600:1406:3a00:21::173e:2e65
    11. /ip6/2600:1406:3a00:21::173e:2e66
    12. /ip6/2600:1406:bc00:53::b81e:94c8

Testing DNS4 (IPv4 only): /dns4/example.com
  Resolved to 6 addresses:
    1. /ip4/96.7.128.198
    2. /ip4/23.192.228.80
    3. /ip4/23.192.228.84
    4. /ip4/23.215.0.136
    5. /ip4/23.215.0.138
    6. /ip4/96.7.128.175

Testing DNS6 (IPv6 only): /dns6/example.com
  Resolved to 6 addresses:
    1. /ip6/2600:1406:bc00:53::b81e:94ce
    2. /ip6/2600:1408:ec00:36::1736:7f24
    3. /ip6/2600:1408:ec00:36::1736:7f31
    4. /ip6/2600:1406:3a00:21::173e:2e65
    5. /ip6/2600:1406:3a00:21::173e:2e66
    6. /ip6/2600:1406:bc00:53::b81e:94c8

Testing DNSADDR (both IPv4 and IPv6): /dnsaddr/example.com
  Resolved to 12 addresses:
    1. /ip4/96.7.128.175
    2. /ip4/96.7.128.198
    3. /ip4/23.192.228.80
    4. /ip4/23.192.228.84
    5. /ip4/23.215.0.136
    6. /ip4/23.215.0.138
    7. /ip6/2600:1406:bc00:53::b81e:94ce
    8. /ip6/2600:1408:ec00:36::1736:7f24
    9. /ip6/2600:1408:ec00:36::1736:7f31
    10. /ip6/2600:1406:3a00:21::173e:2e65
    11. /ip6/2600:1406:3a00:21::173e:2e66
    12. /ip6/2600:1406:bc00:53::b81e:94c8

=== Peer ID Preservation Test with Trio ===
Original address: /dnsaddr/example.com/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
Original peer ID: QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
Resolved to 1 addresses:
  1. /ip4/23.215.0.136/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
     Peer ID: QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN
     Peer ID preserved: True

=== Sequential DNS Resolution with Trio ===

/dns/example.com:
  Resolved to 12 addresses:
    - /ip4/96.7.128.175
    - /ip4/96.7.128.198
    - /ip4/23.192.228.80
    - /ip4/23.192.228.84
    - /ip4/23.215.0.136
    - /ip4/23.215.0.138
    - /ip6/2600:1406:bc00:53::b81e:94ce
    - /ip6/2600:1408:ec00:36::1736:7f24
    - /ip6/2600:1408:ec00:36::1736:7f31
    - /ip6/2600:1406:3a00:21::173e:2e65
    - /ip6/2600:1406:3a00:21::173e:2e66
    - /ip6/2600:1406:bc00:53::b81e:94c8

/dns4/example.com:
  Resolved to 6 addresses:
    - /ip4/23.192.228.84
    - /ip4/23.215.0.136
    - /ip4/23.215.0.138
    - /ip4/96.7.128.175
    - /ip4/96.7.128.198
    - /ip4/23.192.228.80

/dns6/example.com:
  Resolved to 6 addresses:
    - /ip6/2600:1408:ec00:36::1736:7f24
    - /ip6/2600:1408:ec00:36::1736:7f31
    - /ip6/2600:1406:3a00:21::173e:2e65
    - /ip6/2600:1406:3a00:21::173e:2e66
    - /ip6/2600:1406:bc00:53::b81e:94c8
    - /ip6/2600:1406:bc00:53::b81e:94ce

/dnsaddr/example.com:
  Resolved to 12 addresses:
    - /ip4/96.7.128.175
    - /ip4/96.7.128.198
    - /ip4/23.192.228.80
    - /ip4/23.192.228.84
    - /ip4/23.215.0.136
    - /ip4/23.215.0.138
    - /ip6/2600:1406:3a00:21::173e:2e65
    - /ip6/2600:1406:3a00:21::173e:2e66
    - /ip6/2600:1406:bc00:53::b81e:94c8
    - /ip6/2600:1406:bc00:53::b81e:94ce
    - /ip6/2600:1408:ec00:36::1736:7f24
    - /ip6/2600:1408:ec00:36::1736:7f31

=== py-libp2p Integration Example ===

Processing bootstrap node: QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN

Processing bootstrap node: QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN

Processing bootstrap node: QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN

Resolved 0 bootstrap peers:

==================================================
All examples completed!

Summary:
- DNS resolution is working correctly with trio
- Real domains are being resolved to IP addresses
- Peer IDs are preserved during resolution
- All DNS protocols (/dns/, /dns4/, /dns6/, /dnsaddr/) are functional
- Ready for integration with py-libp2p

```

Author: acul71