doc update

docs/tulip_api.md

@@ -56,6 +56,8 @@ ms = tulip.ticks_ms() # returns the milliseconds since boot, aka Arduino millis(
 board = tulip.board() # Returns the board type, e.g. "TDECK", "N16R8" etc
 ```
 
+## Making app packages and screens
+
 If you have a program that relies on mulitple files (graphics, or multiple Python files) you'll want to create a Tulip Package. A package is just a folder with your files in it, like:
 
 ```