[docs] Brush up the documentation

* Try to organize after expected user need
* Update mkdocs stuff and fix a broken link
* Move web building info to building.md
* Add info about Roku Soundbridge
* Add note about Google Nest not working

docs/control-clients/cli-api.md

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+# API and Command Line
+
+You can choose between:
+
+- [The JSON API](#json-api)
+- [A MPD command line client like mpc](#mpc)
+- [DAAP/DACP commands](#daapdacp)
+
+The JSON API is the most versatile and the recommended method, but for simple
+command line operations, mpc is easier. DAAP/DACP is only for masochists.
+
+
+## JSON API
+
+See the [JSON API docs](../json-api.md)
+
+
+## mpc
+
+[mpc](https://www.musicpd.org/clients/mpc/) is easy to use for simple operations
+like enabling speakers, changing volume and getting status.
+
+Due to differences in implementation between OwnTone and MPD, some mpc commands
+will work differently or not at all.
+
+
+## DAAP/DACP
+
+Here is an example of how to use curl with DAAP/DACP. Say you have a playlist
+with a radio station, and you want to make a script that starts playback of that
+station:
+
+1. Run `sqlite3 [your OwnTone db]`. Use `select id,title from files` to get
+    the id of the radio station, and use `select id,title from playlists` to get
+    the id of the playlist.
+2. Convert the two ids to hex.
+3. Put the following lines in the script with the relevant ids inserted (also
+    observe that you must use a session-id < 100, and that you must login and
+    logout):
+
+```shell
+curl "http://localhost:3689/login?pairing-guid=0x1&request-session-id=50"
+curl "http://localhost:3689/ctrl-int/1/playspec?database-spec='dmap.persistentid:0x1'&container-spec='dmap.persistentid:0x[PLAYLIST-ID]'&container-item-spec='dmap.containeritemid:0x[FILE ID]'&session-id=50"
+curl "http://localhost:3689/logout?session-id=50"
+```