moving turtle examples

docs/projects/turtle-spiral.md

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+# Turtle Spiral
+
+## Setting up your project
+
+This project uses an **microturtle** Extension. You'll need to add it to your project to make it work.
+
+* create a new project
+* click on the gearwheel menu and click **Extensions**
+* select the **microturtle** extension
+
+After the project reloads, you should see the **turtle** category in the blocks.
+
+## Code
+
+A turtle that spirals into the center of the display and back out again.
+
+```blocks
+let index = 0
+turtle.setPosition(0, 0)
+turtle.turnRight()
+basic.forever(() => {
+    for (let index = 0; index <= 4; index++) {
+        turtle.forward(4 - index)
+        turtle.turnRight()
+    }
+    for (let index = 0; index <= 4; index++) {
+        turtle.turnLeft()
+        turtle.back(index)
+    }
+})
+```
+
+```package
+microturtle=github:Microsoft/pxt-microturtle#master
+```