mixxx: add common page (#4959)

pages/common/mixxx.md

@@ -0,0 +1,28 @@
+# mixxx
+
+> Free and open source cross-platform DJ software.
+> More information: <https://mixxx.org/manual/latest/chapters/appendix.html#command-line-options>.
+
+- Start the Mixxx GUI in fullscreen:
+
+`mixxx --fullScreen`
+
+- Start in safe developer mode to debug a crash:
+
+`mixxx --developer --safeMode`
+
+- Debug a malfunction:
+
+`mixxx --debugAssertBreak --developer --loglevel trace`
+
+- Start mixxx using the specified settings file:
+
+`mixxx --resourcePath {{mixxx/res/controllers}} --settingsPath {{path/to/settings-file}}`
+
+- Debug a custom controller mapping:
+
+`mixxx --controllerDebug --resourcePath {{path/to/mapping-directory}}`
+
+- Show command line help:
+
+`mixxx --help`