update docs

README.md

@@ -63,7 +63,8 @@ Too many dependencies? Because OpenSCAD doesn't provide namespace management, I
 	- [paths2sections](https://openhome.cc/eGossip/OpenSCAD/lib-paths2sections.html)
 	
 - Path
-    - [circle_path](https://openhome.cc/eGossip/OpenSCAD/lib-circle_path.html)
+    - [arc_path](https://openhome.cc/eGossip/OpenSCAD/lib-arc_path.html)
+	- [circle_path](https://openhome.cc/eGossip/OpenSCAD/lib-circle_path.html)
     - [bezier_curve](https://openhome.cc/eGossip/OpenSCAD/lib-bezier_curve.html)
 	- [bezier_surface](https://openhome.cc/eGossip/OpenSCAD/lib-bezier_surface.html)
 	- [bezier_smooth](https://openhome.cc/eGossip/OpenSCAD/lib-bezier_smooth.html)

docs/lib-arc_path.md

@@ -0,0 +1,32 @@
+# arc_path
+
+Creates an arc path. You can pass a 2 element vector to define the central angle. Its `$fa`, `$fs` and `$fn` parameters are consistent with the `circle` module. 
+
+## Parameters
+
+- `radius` : The radius of the circle.
+- `angle` : A single value or a 2 element vector which defines the central angle. The first element of the vector is the beginning angle in degrees, and the second element is the ending angle.
+- `$fa`, `$fs`, `$fn` : Check [the circle module](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_the_2D_Subsystem#circle) for more details.
+
+
+## Examples
+  
+    include <arc_path.scad>;
+    include <hull_polyline2d.scad>;
+    
+    $fn = 24;
+    points = arc_path(radius = 20, angle = [45, 290], width = 2);
+    hull_polyline2d(points);
+
+![arc_path](images/lib-arc_path-1.JPG)
+
+    include <arc_path.scad>;
+    include <hull_polyline2d.scad>;
+    
+    $fn = 24;
+    points = arc_path(radius = 20, angle = 135, width = 2);
+    hull_polyline2d(points);
+
+![arc_path](images/lib-arc_path-2.JPG)
+
+