Updated the stitching module docs

modules/stitching/doc/camera.rst

+Camera
+======
+
+.. highlight:: cpp
+
+detail::CameraParams
+--------------------
+.. ocv:class:: detail::CameraParams
+
+Describes camera parameters.
+
+.. note:: Translation is assumed to be zero during the whole stitching pipeline. 
+
+::
+
+    struct CV_EXPORTS CameraParams
+    {
+        CameraParams();
+        CameraParams(const CameraParams& other);
+        const CameraParams& operator =(const CameraParams& other);
+        Mat K() const;
+
+        double focal; // Focal length
+        double aspect; // Aspect ratio
+        double ppx; // Principal point X
+        double ppy; // Principal point Y
+        Mat R; // Rotation
+        Mat t; // Translation
+    };

modules/stitching/doc/stitching.rst

@@ -6,6 +6,7 @@ stitching. Images stitching
     :maxdepth: 2
     
     high_level
+    camera
     matching
     motion_estimation
     autocalib