Add sample code for ApplePi.
user
```assembly
# Example code, just demonstrating each instruction
  add $2 $0
  sub $3 $1
  rand $4 5
label:
  load $6 $7
  store $8 $9
  jal label
  jr $10
  beq $11 label
  bgt $12 label
  set $13 $14
  seti $15 16
```
assistant