Misc. ./apps ./doc ./platoforms typos

Found via `codespell -q 3 --skip="./3rdparty" -I ../opencv-whitelist.txt`

doc/tutorials/features2d/feature_flann_matcher/feature_flann_matcher.markdown

@@ -84,7 +84,7 @@ int main( int argc, char** argv )
   printf("-- Min dist : %f \n", min_dist );
 
   //-- Draw only "good" matches (i.e. whose distance is less than 2*min_dist,
-  //-- or a small arbitary value ( 0.02 ) in the event that min_dist is very
+  //-- or a small arbitrary value ( 0.02 ) in the event that min_dist is very
   //-- small)
   //-- PS.- radiusMatch can also be used here.
   std::vector< DMatch > good_matches;