WindReferece.md added in local pathfinding to document wind coord system conventions

Author: raghumanimehta

src/local_pathfinding/WindReference.md

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+# Wind Conventions Reference
+
+## Coordinate Systems
+
+### Global Coordinate System
+
+- Uses true bearing conventions (geographic/earth frame)
+- **0° = North**, increases clockwise till 180°, decrease counter-clockwise till -180° (exclusive)
+- Range: (-180, 180] degrees
+- Used for true wind direction and boat heading
+
+### Boat Coordinate System
+
+- Relative to the boat's orientation
+- **0° = directly opposite to the boat's heading** (bow to stern direction)
+- Increases clockwise till 180°, decrease counter-clockwise till -180° (exclusive) relative to the boat
+- Range: (-180, 180] degrees
+- Used for apparent wind direction (sensor readings)
+
+## Wind Types
+
+### True Wind
+
+- Wind velocity in the global/geographic coordinate frame
+- What a stationary observer on the ground would measure
+- **0° = wind blowing FROM north TO south** (meteorological convention)
+- Independent of boat motion
+
+### Boat Wind
+
+- Wind created by the boat's own motion through the air
+- Direction: opposite of boat heading (`boat_heading + 180°`)
+- Speed: equal to boat speed
+
+### Apparent Wind
+
+- Wind experienced on the moving boat
+- Measured relative to the boat (boat coordinate system)
+- Combination of true wind + boat-induced wind
+- **Apparent Wind = True Wind + Boat Wind**
+
+## Conversion Functions
+
+Available in [`wind_coord_systems.py`](local_pathfinding/wind_coord_systems.py):
+
+### Coordinate System Conversions
+
+- `boat_to_global_coordinate(boat_heading, wind_direction)` - Convert boat-frame wind to global-frame bearing
+- `global_to_boat_coordinate(boat_heading, global_wind_direction)` - Convert global-frame wind to boat-frame
+
+### Wind Conversions
+
+- `get_true_wind(aw_dir_deg, aw_speed_kmph, boat_heading_deg, boat_speed_kmph, ret_rad)`  
+  Calculate true wind from apparent wind
+- `get_apparent_wind(tw_dir_deg, tw_speed_kmph, boat_heading_deg, boat_speed_kmph, ret_rad)`  
+  Calculate apparent wind from true wind
+
+## Key Notes
+
+- All angles use **meteorological convention**: wind direction indicates where wind is **coming from**, not going to
+- The math computes vectors in the direction wind travels, but by convention we interpret them as source directions
+- Boat coordinate 0° points to the stern (opposite of heading) following true bearing conventions