Don't use ```block in tutorials. (#588)

docs/tutorials/make-an-animation.md

@@ -10,7 +10,7 @@ Create a custom animation for your @boardname@.
 
 Open the ``||brick:Brick||`` Toolbox drawer. Drag out a ``||brick:show string||`` block onto the Workspace, and drop it into the ``||loops:on Start||`` block. You should hear and see the block click into place.
 
-```block
+```blocks
 brick.showString("Hello world", 1) 
 ```
 

docs/tutorials/what-animal-am-i.md

@@ -10,7 +10,7 @@ Create different animal effects with your @boardname@.
 
 Open the ``||brick:Brick||`` Toolbox drawer. Drag out a ``||brick:show string||`` block from the **Screen** section onto the Workspace, and drop it into the ``||loops:on start||`` block. You should hear and see the block click into place.
 
-```block
+```blocks
 brick.showString("Hello world", 1)
 ```