Added FREAK-descriptor extractor to documentation.

Previously it was missing.
Ordered all descriptors by year of first publication.

modules/features2d/doc/common_interfaces_of_descriptor_extractors.rst

@@ -78,9 +78,10 @@ The current implementation supports the following types of a descriptor extracto
 
  * ``"SIFT"`` -- :ocv:class:`SIFT`
  * ``"SURF"`` -- :ocv:class:`SURF`
- * ``"ORB"`` -- :ocv:class:`ORB`
- * ``"BRISK"`` -- :ocv:class:`BRISK`
  * ``"BRIEF"`` -- :ocv:class:`BriefDescriptorExtractor`
+ * ``"BRISK"`` -- :ocv:class:`BRISK`
+ * ``"ORB"`` -- :ocv:class:`ORB`
+ * ``"FREAK"`` -- :ocv:class:`FREAK`
 
 A combined format is also supported: descriptor extractor adapter name ( ``"Opponent"`` --
 :ocv:class:`OpponentColorDescriptorExtractor` ) + descriptor extractor name (see above),