Add Chapter 6 python files and fix grammar issues in readme

thinkcspy/Chapter-6-Exercises/Python-files/problem2.py

@@ -0,0 +1,36 @@
+# Runestone.Academy thinkcspy course
+# Chapter 6
+# Problem 2
+
+import turtle
+
+def drawSquare(t, sz):
+    """Get turtle t to draw a square of sz side"""
+
+    for i in range(4):
+        t.forward(sz)
+        t.left(90)
+
+wn = turtle.Screen()
+wn.bgcolor("lightgreen")
+
+alex = turtle.Turtle()
+alex.color("pink")
+alex.pensize(2)
+
+
+def drawStackedSquares(tt, num):
+    for i in range(num):
+        drawSquare(tt, 20*(i+1))
+        tt.up()
+        tt.backward(10)
+        tt.left(90)
+        tt.backward(10)
+        tt.right(90)
+        tt.down()
+        
+
+drawStackedSquares(alex, 5)        
+        
+
+wn.exitonclick()