Update README.md

modules/saliency/README.md

-Saliency API, understanding where humans focus given a scene
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+Saliency API, Where to Focus in a Scene
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-The purpose of this module is to create, group and make available to the users, different saliency algorithms, belonging to different categories.
+The purpose of this module is to create, group and make available to the users, different saliency algorithms, belonging to different categories. Saliency API -- Where humans would look in a scene. Has routines for static, motion and "objectness" saliency.