Implement changes for downloadable zilla-examples

[vordimous]

This PR:

• Add the mqtt.kafka.broker example as a guide
• Add a generic TLS & SSL section

Releasing along with https://github.com/aklivity/zilla-examples/pull/86

1. Merge this PR to develop, ignoring the broken links (they will be fixed by the end)
2. Merge https://github.com/aklivity/zilla-examples/pull/86 which points to docs/next to main
3. Create release v1 (Or whichever version scheme is preferred) on zilla/examples
4. Release docs to latest
5. update zilla/examples docs links to point to '/latest'