Update 'README.md'

+ if __name__ == '__main__':
    main()

README.md

@@ -162,4 +162,7 @@ def main():
         erase_karel(karel_east_mirrored)
         erase_karel(karel_west)
         erase_karel(karel_west_mirrored)
+
+if __name__ == '__main__':
+    main()
 ```