Doc: Fixed random QDoc warnings

- Fixed \snippet paths
- Minor language edits
- Removed unnecessary multiple page commands in a single comment
block. For example, \fn and \qmlsignal in a single comment block
is not allowed. Such instances must be documented in separate
comment blocks.

Change-Id: I65f4518499e2600c4e1807356d4116c575e48c19
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
(cherry picked from commit 51334d2995)

src/multimedia/doc/src/cameraoverview.qdoc

@@ -104,14 +104,17 @@ In QML, you can use \l Camera and \l VideoOutput together to show a
 simple viewfinder:
 
 \qml
+import QtQuick 2.0
+import QtMultimedia 5.0
+
+VideoOutput {
+    source: camera
+
     Camera {
         id: camera
         // You can adjust various settings in here
     }
-
-    VideoOutput {
-        source: camera
-    }
+}
 \endqml
 
 In C++, your choice depends on whether you are using widgets, or QGraphicsView.

src/multimedia/doc/src/multimedia.qdoc

@@ -176,14 +176,14 @@ change when porting code.
 
 \section2 QML Types
 The following types are accessed by using:
-\qml
+\code
 import QtMultimedia 5.0
-\endqml
+\endcode
 \annotatedlist multimedia_qml
 The following types are accessed by using \l {Positional Audio} {QtAudioEngine}:
-\qml
+\code
 import QtAudioEngine 1.0
-\endqml
+\endcode
 \annotatedlist multimedia_audioengine
 
 \section2 Multimedia Classes