[docs] Generate OwnTone documentation with MkDocs

- Copy existing README*.md and INSTALL.md files to docs folder
- Set up MkDocs to build documentation (mkdocs.yml)
- Add new index.md with a quick overview of OwnTone

mkdocs.yml

@@ -0,0 +1,126 @@
+# Copyright (C) 2022 Christian Meffert <christian.meffert@googlemail.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+# Project information
+site_name: OwnTone
+site_url: https://owntone.github.io/owntone-server/
+site_author: OwnTone maintainers
+site_description: >-
+  Linux/FreeBSD DAAP (iTunes) and MPD media server with support for AirPlay
+  devices (multiroom), Apple Remote (and compatibles), Chromecast, Spotify
+  and internet radio. 
+
+# Repository
+repo_name: owntone/owntone-server
+repo_url: https://github.com/owntone/owntone-server
+#edit_uri: ""
+
+# Configuration
+theme:
+  name: 'material'
+  language: en
+  features:
+#    - navigation.tabs
+    - navigation.sections
+  palette:
+    - scheme: default
+      primary: white
+      accent: teal
+      toggle:
+        icon: material/toggle-switch
+        name: Switch to dark mode
+    - scheme: slate
+      primary: blue grey
+      accent: teal
+      toggle:
+        icon: material/toggle-switch-off-outline
+        name: Switch to light mode
+  font:
+    text: Roboto
+    code: Roboto Mono
+  favicon: assets/favicon.ico
+  logo: assets/logo.svg
+
+# Plugins
+plugins:
+  - search
+  - minify:
+      minify_html: true
+
+# Customization
+extra:
+  social:
+    - icon: fontawesome/brands/github
+      link: https://github.com/owntone/owntone-server
+
+extra_css:
+  - assets/extra.css
+
+extra_javascript:
+  - assets/extra.js
+
+# Extensions
+markdown_extensions:
+  - abbr
+  - admonition
+  - attr_list
+  - def_list
+  - footnotes
+  - meta
+  - md_in_html
+  - toc:
+      permalink: true
+  - pymdownx.arithmatex:
+      generic: true
+  - pymdownx.betterem:
+      smart_enable: all
+  - pymdownx.caret
+  - pymdownx.details
+  - pymdownx.emoji:
+      emoji_generator: !!python/name:materialx.emoji.to_svg
+      emoji_index: !!python/name:materialx.emoji.twemoji
+  - pymdownx.highlight:
+      anchor_linenums: true
+  - pymdownx.inlinehilite
+  - pymdownx.keys
+  - pymdownx.magiclink:
+      repo_url_shorthand: true
+      user: squidfunk
+      repo: mkdocs-material
+  - pymdownx.mark
+  - pymdownx.smartsymbols
+  - pymdownx.superfences:
+      custom_fences:
+        - name: mermaid
+          class: mermaid
+          format: !!python/name:pymdownx.superfences.fence_code_format
+  - pymdownx.tabbed:
+      alternate_style: true
+  - pymdownx.tasklist:
+      custom_checkbox: true
+  - pymdownx.tilde
+
+# Page tree
+nav:
+  - Home: index.md
+  - Documentation: documentation.md
+  - Installation: installation.md
+  - Smart playlists: smart-playlists.md
+  - JSON API: json-api.md
+  - Web interface: web-interface.md
+  - Alsa: outputs-alsa.md
+  - Pulse audio: outputs-pulse.md
+  - Radio streams: radio-streams.md