audtool: add page (#12881)

Co-authored-by: spageektti <git@spageektti.cc>

pages/common/audtool.md

@@ -0,0 +1,36 @@
+# audtool
+
+> Control Audacious using commands.
+> More information: <https://manned.org/audtool>.
+
+- Play/pause audio playback:
+
+`audtool playback-playpause`
+
+- Print artist, album, and song name of currently playing song:
+
+`audtool current-song`
+
+- Set volume of audio playback:
+
+`audtool set-volume {{100}}`
+
+- Skip to the next song:
+
+`audtool playlist-advance`
+
+- Print the bitrate of the current song in kilobits:
+
+`audtool current-song-bitrate-kbps`
+
+- Open audacious in full-screen if hidden:
+
+`audtool mainwin-show`
+
+- Display help:
+
+`audtool help`
+
+- Display settings:
+
+`audtool preferences-show`