Docs: Limit code rendering to relevant sections in multiversion webhook tutorial

[camilamacedo86]

See; https://deploy-preview-5230--kubebuilder.netlify.app/multiversion-tutorial/webhooks#webhook-setup-for-v2

We should show only the validation logic from

And from main only the setup:

We should not show the whole file. Instead we should only render the relevant code.

[BadisLaffet1]

/assign