add heredoc to perspective

Pod/Classes/Perspective+Transform.swift

@@ -7,16 +7,40 @@
 //
 
 public extension Perspective {
+    /**
+     Create Perspective based on 4 points
+
+     - parameter topLeft: top left corner
+     - parameter topRight: top right corner
+     - parameter bottomLeft: bottom left corner
+     - parameter bottomRight: bottom right corner
+     */
     public convenience init(_ topLeft:CGPoint, _ topRight:CGPoint, _ bottomLeft:CGPoint, _ bottomRight:CGPoint) {
         self.init(Quadrilateral(topLeft, topRight, bottomLeft, bottomRight))
     }
+    /**
+     Create Perspective based on 4 points
+
+     - parameter points: corner points, must be size 4
+     */
     public convenience init(_ points:[CGPoint]) {
         self.init(Quadrilateral(points))
     }
+    /**
+        Create Perspective based on 4 corners of the rectangle
+
+        - parameter rect: defines the corners
+     */
     public convenience init(_ rect:CGRect) {
         self.init(Quadrilateral(rect))
     }
 
+    /**
+         Calculate CATransform3D to another perspective
+
+         - parameter destination: perspective to transform to
+         - returns: tranformation matrix from this perspective to destination
+     */
     public func projectiveTransform(destination:Perspective) -> CATransform3D {
         return CATransform3D(projection(to: destination).to3d())
     }