Add Chapter 6 python files and fix grammar issues in readme

thinkcspy/Chapter-6-Exercises/Python-files/problem17.py

@@ -0,0 +1,32 @@
+# Runestone.Academy thinkcspy course
+# Chapter 6
+# Problem 17
+
+import turtle
+
+def drawSprite(t, numSides, legLength):
+    angle = 360/numSides
+    
+    for i in range(numSides):
+        t.forward(legLength)
+        t.up()
+        t.forward(-legLength)    
+        t.right(angle)
+        t.down()
+
+def fancySquare(tt, sz):
+    """Get turtle t to draw a square of sz side"""
+
+    for i in range(4):
+        drawSprite(tt, int(sz/10), int(sz/20))
+        tt.forward(sz)
+        tt.left(90)
+
+wn = turtle.Screen()
+wn.bgcolor("lightblue")
+
+alex = turtle.Turtle()
+alex.color("maroon")
+alex.pensize(2)
+
+fancySquare(alex, 100)