feat(example): adds support for request ID propagation in logs.

[jcchavezs]

This PR adds example code on how to propagate the request ID to the matched rules log cc @fardin01

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[M4tteoP]

Context: #1119.

Is this PR something that we want to merge to keep evident how this can be implemented? Or was it intended just to show it?
If I'm getting this right, in the context of the request, this solution should be ported to Caddy and rely on x-request-id header as the extra provided request_id.

[fzipi]

@jcchavezs @M4tteoP Do we close? Do we push this?