Update Research_Pylot-Planning_PAF21-Perception.md: GIFs added

doc/03_research/research_PAF_23/Research_Pylot-Planning_PAF21-Perception.md

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 - **Waypoint Planner**: Auto follows predefined waypoints. It recognizes traffic lights and stops at obstacles, but cannot avoid them
 - **Freenet-Optimal-Trajecotry-Planner**: CPP code with Python wrapper ([GitHub](https://github.com/erdos-project/frenet_optimal_trajectory_planner))
 → Predefined line that is used for orientation → Can avoid obstacles!
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+![freenet_gif](https://github.com/erdos-project/frenet_optimal_trajectory_planner/raw/master/img/fot2.gif)
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 - **RRT\*-Planner**: RRT* algorithm to plan the path ([GitHub](https://github.com/erdos-project/rrt_star_planner))
   - Creates random nodes
   - Adds nodes to the graph that are not blocked by objects on the road
   - Generally terminates as soon as a node is found in the target area
   - RRT*: Searches for the shortest path
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+![rrt_star_gif](https://github.com/erdos-project/rrt_star_planner/raw/master/img/rrtstar.gif)
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 - **Hybrid A\* planner**: Hybrid A* algorithm for route planning ([GitHub](https://github.com/erdos-project/hybrid_astar_planner))
   - Calculates the shortest path between two nodes from a graph
   - Similar to Dijkstra's algorithm
   - Nodes are estimated based on their costs and promising nodes are selected first
   - Hybrid A* algorithm: Not always optimal solution, but in the neighborhood of the optimal solution.
 
+![hybrid_astar_gif](https://github.com/erdos-project/hybrid_astar_planner/raw/master/img/straight_obstacle.gif)
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 ## PAF 21-2
 
 ### Perception