Add workflow to deploy PouchDB website to pouchdb-site/asf-site

[espy]

Overview

Hello 👋 This PR adds a GH workflow to deploy the PouchDB website to the branch asf-site in the repo apache/pouchdb-site, from where it will then be hosted somehow.

The workflow builds the site via npm run build-site , checks out the apache/pouchdb-site repo and pushes the build folder contents into asf-site.

Testing recommendations

This will need some manual testing after merging into master, since the workflow only runs on that branch. Make small changes to anything in the docs folder on master, and observe whether https://github.com/apache/pouchdb-site/tree/asf-site and the associated https://pouchdb.apache.org/ now contain the changes you made.

Checklist

• I am not a bot
• This is my own work, I did not use AI, LLM's or similar technology for code or docs generation
• Code is written and works correctly 👉 Deployment action works in our org at least