Restructure headscale documentation (#2163)

* Setup mkdocs-redirects

* Restructure existing documentation

* Move client OS support into the documentation

* Move existing Client OS support table into its own documentation page
* Link from README.md to the rendered documentation
* Document minimum Tailscale client version

* Reuse CONTRIBUTING.md" in the documentation

* Include "CONTRIBUTING.md" from the repository root
* Update FAQ and index page and link to the contributing docs

* Add configuration reference

* Add a getting started page and explain the first steps with headscale

* Use the existing "Using headscale" sections and combine them into a
  single getting started guide with a little bit more explanation.
* Explain how to get help from the command line client.
* Remove duplicated sections from existing installation guides

* Document requirements and assumptions

* Document packages provided by the community

* Move deb install guide to official releases

* Move manual install guide to official releases

* Move container documentation to setup section

* Move sealos documentation to cloud install page

* Move OpenBSD docs to build from source

* Simplify DNS documentation

* Add sponsor page

* Add releases page

* Add features page

* Add help page

* Add upgrading page

* Adjust mkdocs nav

* Update wording

Use the term headscale for the project, Headscale on the beginning of a
sentence and `headscale` when refering to the CLI.

* Welcome to headscale

* Link to existing documentation in the FAQ

* Remove the goal header and use the text as opener

* Indent code block in OIDC

* Make a few pages linter compatible

Also update ignored files for prettier

* Recommend HTTPS on port 443

Fixes: #2164

* Use hosts in acl documentation

thx @efficacy38 for noticing this

Ref: #1863

* Use mkdocs-macros to set headscale version once

docs/windows-client.md

@@ -1,61 +0,0 @@
-# Connecting a Windows client
-
-## Goal
-
-This documentation has the goal of showing how a user can use the official Windows [Tailscale](https://tailscale.com) client with `headscale`.
-
-!!! info "Instructions on your headscale instance"
-
-    An endpoint with information on how to connect your Windows device
-    is also available at `/windows` on your running instance.
-
-## Installation
-
-Download the [Official Windows Client](https://tailscale.com/download/windows) and install it.
-
-## Configuring the headscale URL
-
-Open a Command Prompt or Powershell and use Tailscale's login command to connect with your headscale instance (e.g
-`https://headscale.example.com`):
-
-```
-tailscale login --login-server <YOUR_HEADSCALE_URL>
-```
-
-Follow the instructions in the opened browser window to finish the configuration.
-
-## Troubleshooting
-
-### Unattended mode
-
-By default, Tailscale's Windows client is only running when the user is logged in. If you want to keep Tailscale running
-all the time, please enable "Unattended mode":
-
-- Click on the Tailscale tray icon and select `Preferences`
-- Enable `Run unattended`
-- Confirm the "Unattended mode" message
-
-See also [Keep Tailscale running when I'm not logged in to my computer](https://tailscale.com/kb/1088/run-unattended)
-
-### Failing node registration
-
-If you are seeing repeated messages like:
-
-```
-[GIN] 2022/02/10 - 16:39:34 | 200 |    1.105306ms |       127.0.0.1 | POST     "/machine/redacted"
-```
-
-in your `headscale` output, turn on `DEBUG` logging and look for:
-
-```
-2022-02-11T00:59:29Z DBG Machine registration has expired. Sending a authurl to register machine=redacted
-```
-
-This typically means that the registry keys above was not set appropriately.
-
-To reset and try again, it is important to do the following:
-
-1. Shut down the Tailscale service (or the client running in the tray)
-2. Delete Tailscale Application data folder, located at `C:\Users\<USERNAME>\AppData\Local\Tailscale` and try to connect again.
-3. Ensure the Windows node is deleted from headscale (to ensure fresh setup)
-4. Start Tailscale on the Windows machine and retry the login.