add existing documentation

doc/sample/Vehicle.im

@@ -0,0 +1,44 @@
+package net.doorstuck.vehicles
+
+protocol Vehicle
+    - startup
+    - shutdown
+    - nrWheels
+    - nrDoors
+    - turn(direction:dir)
+    - accelerate(direction:dir)
+    - velocity
+end
+
+class Car <Vehicle>
+    - startup
+        self.engineRunning = true
+    end
+
+    - shutdown
+        self.engineRunning = false
+    end
+
+    - nrWheels
+        ^4
+    end
+
+    - nrDoors
+        ^4
+    end
+
+    - turn(direction:dir)
+        self.currentDirection = dir
+    end
+
+    - accelerate(direction:dir)
+        match dir
+            #forward => self.currentVelocity += 1,
+            #backward => self.currentVelocity -= 1,
+        end
+    end
+
+    - velicity
+        ^self.currentVelocity
+    end
+end