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

mkdocs.yml

@@ -66,9 +66,26 @@ exclude_docs: |
 plugins:
   - search:
       separator: '[\s\-,:!=\[\]()"`/]+|\.(?!\d)|&[lg]t;|(?!\b)(?=[A-Z][a-z])'
+  - macros:
+  - include-markdown:
   - minify:
       minify_html: true
   - social: {}
+  - redirects:
+      redirect_maps:
+        acls.md: ref/acls.md
+        android-client.md: usage/connect/android.md
+        apple-client.md: usage/connect/apple.md
+        dns-records.md: ref/dns.md
+        exit-node.md: ref/exit-node.md
+        faq.md: about/faq.md
+        iOS-client.md: usage/connect/apple.md#ios
+        oidc.md: ref/oidc.md
+        remote-cli.md: ref/remote-cli.md
+        reverse-proxy.md: ref/integration/reverse-proxy.md
+        tls.md: ref/tls.md
+        web-ui.md: ref/integration/web-ui.md
+        windows-client.md: usage/connect/windows.md
 
 # Customization
 extra:
@@ -83,6 +100,8 @@ extra:
       link: https://github.com/juanfont/headscale/pkgs/container/headscale
     - icon: fontawesome/brands/discord
       link: https://discord.gg/c84AZQhmpx
+  headscale:
+    version: 0.23.0
 
 # Extensions
 markdown_extensions:
@@ -128,23 +147,39 @@ markdown_extensions:
 
 # Page tree
 nav:
-  - Home: index.md
-  - FAQ: faq.md
-  - Getting started:
+  - Welcome: index.md
+  - About:
+      - FAQ: about/faq.md
+      - Features: about/features.md
+      - Clients: about/clients.md
+      - Getting help: about/help.md
+      - Releases: about/releases.md
+      - Contributing: about/contributing.md
+      - Sponsor: about/sponsor.md
+
+  - Setup:
+      - Requirements and Assumptions: setup/requirements.md
       - Installation:
-          - Linux: running-headscale-linux.md
-          - OpenBSD: running-headscale-openbsd.md
-          - Container: running-headscale-container.md
-      - Configuration:
-          - Web UI: web-ui.md
-          - OIDC authentication: oidc.md
-          - Exit node: exit-node.md
-          - Reverse proxy: reverse-proxy.md
-          - TLS: tls.md
-          - ACLs: acls.md
-          - Custom DNS records: dns-records.md
-          - Remote CLI: remote-cli.md
-      - Usage:
-          - Android: android-client.md
-          - Apple: apple-client.md
-          - Windows: windows-client.md
+          - Official releases: setup/install/official.md
+          - Community packages: setup/install/community.md
+          - Container: setup/install/container.md
+          - Cloud: setup/install/cloud.md
+          - Build from source: setup/install/source.md
+      - Upgrade: setup/upgrade.md
+  - Usage:
+      - Getting started: usage/getting-started.md
+      - Connect a node:
+          - Android: usage/connect/android.md
+          - Apple: usage/connect/apple.md
+          - Windows: usage/connect/windows.md
+  - Reference:
+      - Configuration: ref/configuration.md
+      - OIDC authentication: ref/oidc.md
+      - Exit node: ref/exit-node.md
+      - TLS: ref/tls.md
+      - ACLs: ref/acls.md
+      - DNS: ref/dns.md
+      - Remote CLI: ref/remote-cli.md
+      - Integration:
+          - Reverse proxy: ref/integration/reverse-proxy.md
+          - Web UI: ref/integration/web-ui.md