Docs deploy to GitHub Pages from develop for faster iteration cycles.
Main was failing the deploy step with "Branch 'main' is not allowed to
deploy to github-pages due to environment protection rules" on every
release merge (v3.2.0, v3.3.0) — noise without signal, since docs
weren't meant to serve from main anyway.
Removes main from both the push trigger and the deploy-job guard.
Develop continues to deploy as before; manual dispatch still works.
Igor Lins e Silva