Added some documentation for MSER

doc/opencv.bib

@@ -848,3 +848,19 @@
   year={2007},
   publisher={Springer}
 }
+@incollection{nister2008linear,
+  title={Linear time maximally stable extremal regions},
+  author={Nist{\'e}r, David and Stew{\'e}nius, Henrik},
+  booktitle={Computer Vision--ECCV 2008},
+  pages={183--196},
+  year={2008},
+  publisher={Springer}
+}
+@inproceedings{forssen2007maximally,
+  title={Maximally stable colour regions for recognition and matching},
+  author={Forss{\'e}n, Per-Erik},
+  booktitle={Computer Vision and Pattern Recognition, 2007. CVPR'07. IEEE Conference on},
+  pages={1--8},
+  year={2007},
+  organization={IEEE}
+}