Fix up a few doc issues

* lingering references to Mobility
* missing group tags on some classes meant they went missing
* put classes into functional groups as well (e.g. audio, camera)
* added some of the qdoc files to OTHER_FILES so they show up in Creator

There are still a lot of warnings since it seems like qdoc is not
processing the controls directory.

Change-Id: I036f8826ae63f8273b3e649cb32c091d964ce830
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>

src/multimedia/audio/qsoundeffect.cpp

@@ -54,6 +54,7 @@ QT_BEGIN_NAMESPACE
     \brief The SoundEffect element provides a way to play sound effects in QML.
 
     \inmodule QtMultimedia
+    \ingroup multimedia_qml
 
     This element is part of the \bold{QtMultimedia 5.0} module.
 
@@ -62,6 +63,17 @@ QT_BEGIN_NAMESPACE
     \snippet doc/src/snippets/multimedia-snippets/soundeffect.qml complete snippet
 */
 
+/*!
+    \class QSoundEffect
+    \brief The QSoundEffect provides a way to play low latency sound effects.
+
+    \ingroup multimedia
+    \ingroup multimedia_audio
+
+*/
+
+
+
 /*!
     \qmlproperty url SoundEffect::source