added example script for draw.polygon function

doc/examples/plot_polygon.py

@@ -0,0 +1,39 @@
+"""
+============
+Fill polygon
+============
+
+This example shows how to fill polygons in images.
+"""
+
+import matplotlib.pyplot as plt
+
+from skimage.draw import polygon
+import numpy as np
+
+
+img = np.zeros((500, 500), 'uint8')
+polygon1 = np.array((
+    (50, 50),
+    (150, 30),
+    (400, 100),
+    (300, 200),
+    (480, 400),
+    (100, 420),
+    (50, 50),
+))
+polygon2 = np.array((
+    (300, 300),
+    (480, 320),
+    (380, 430),
+    (220, 590),
+    (300, 300),
+))
+rr, cc = polygon(polygon1, img.shape)
+img[rr,cc] = 127
+rr, cc = polygon(polygon2, img.shape)
+img[rr,cc] = 255
+
+plt.gray()
+plt.imshow(img)
+plt.show()