Doxygen tutorials: warnings cleared

doc/tutorials/features2d/feature_description/feature_description.markdown

@@ -8,7 +8,7 @@ In this tutorial you will learn how to:
 
 -   Use the @ref cv::DescriptorExtractor interface in order to find the feature vector correspondent
     to the keypoints. Specifically:
-    -   Use @ref cv::SurfDescriptorExtractor and its function @ref cv::compute to perform the
+    -   Use @ref cv::xfeatures2d::SURF and its function @ref cv::xfeatures2d::SURF::compute to perform the
         required calculations.
     -   Use a @ref cv::BFMatcher to match the features vector
     -   Use the function @ref cv::drawMatches to draw the detected matches.
@@ -78,14 +78,13 @@ int main( int argc, char** argv )
  void readme()
  { std::cout << " Usage: ./SURF_descriptor <img1> <img2>" << std::endl; }
 @endcode
+
 Explanation
 -----------
 
 Result
 ------
 
-1.  Here is the result after applying the BruteForce matcher between the two original images:
-
-    ![image](images/Feature_Description_BruteForce_Result.jpg)
-
+Here is the result after applying the BruteForce matcher between the two original images:
 
+![image](images/Feature_Description_BruteForce_Result.jpg)

doc/tutorials/features2d/feature_detection/feature_detection.markdown

@@ -7,7 +7,7 @@ Goal
 In this tutorial you will learn how to:
 
 -   Use the @ref cv::FeatureDetector interface in order to find interest points. Specifically:
-    -   Use the @ref cv::SurfFeatureDetector and its function @ref cv::detect to perform the
+    -   Use the @ref cv::xfeatures2d::SURF and its function @ref cv::xfeatures2d::SURF::detect to perform the
         detection process
     -   Use the function @ref cv::drawKeypoints to draw the detected keypoints
 
@@ -72,6 +72,7 @@ int main( int argc, char** argv )
   void readme()
   { std::cout << " Usage: ./SURF_detector <img1> <img2>" << std::endl; }
 @endcode
+
 Explanation
 -----------
 
@@ -85,5 +86,3 @@ Result
 2.  And here is the result for the second image:
 
     ![image](images/Feature_Detection_Result_b.jpg)
-
-

doc/tutorials/features2d/feature_flann_matcher/feature_flann_matcher.markdown

@@ -7,7 +7,7 @@ Goal
 In this tutorial you will learn how to:
 
 -   Use the @ref cv::FlannBasedMatcher interface in order to perform a quick and efficient matching
-    by using the @ref cv::FLANN ( *Fast Approximate Nearest Neighbor Search Library* )
+    by using the @ref flann module
 
 Theory
 ------
@@ -123,6 +123,7 @@ int main( int argc, char** argv )
 void readme()
 { std::cout << " Usage: ./SURF_FlannMatcher <img1> <img2>" << std::endl; }
 @endcode
+
 Explanation
 -----------
 
@@ -136,5 +137,3 @@ Result
 2.  Additionally, we get as console output the keypoints filtered:
 
     ![image](images/Feature_FlannMatcher_Keypoints_Result.jpg)
-
-