updating DIRECTORY.md

DIRECTORY.md

@@ -70,6 +70,7 @@
   * [Tree Height](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/dynamic_programming/tree_height.cpp)
 
 ## Geometry
+  * [Jarvis Algorithm](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/geometry/jarvis_algorithm.cpp)
   * [Line Segment Intersection](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/geometry/line_segment_intersection.cpp)
 
 ## Graph