Reorganize and update reverse proxy documentation

[bens95]

This is the beginning of my attempts to improve/modernize reverse proxy documentation. The reverse proxy docs are very verbose, and did not include information for apache configs. I split them up in this manner for two reasons:

1. The existing docs are very verbose and would be a lot to throw at someone at once
2. Nobody who is reading docs for one proxy really needs to read another

I also question whether some of the content in these docs belongs on an OpenHAB wiki at all. While the documentation is good, it is overly detailed. Things like purchasing a domain, letsencrypt cert generation, webserver installation, etc are better documented on their own wikis/elsewhere. If I were starting from scratch, these pages would be one article with:

• prerequisites (a domain, a cert, knowledge of your chosen webserver)
• mention of common best practices (auth, https)
• OpenHAB specific settings (with syntax from each webserver)
• sample configs

However I would feel bad removing all of the work that has already been done. Thoughts?

[netlify]

✅ Thanks for your pull request to the openHAB documentation! The result can be previewed at the URL below (this comment and the preview will be updated if you add more commits).

Built without sensitive environment variables

Name	Link
🔨 Latest commit	5cf0e3e
🔍 Latest deploy log	https://app.netlify.com/sites/openhab-docs-preview/deploys/67a911314b2a0f00081e653e
😎 Deploy Preview	https://deploy-preview-2456--openhab-docs-preview.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.