clarify on.code_change

Dependencies

• [2] WZZGVKSG a few more renames
• [3] NVVHJWJE a new event: receiving code changes from the driver
• [4] 5OVKHVY6 nice way to make on.* handlers more discoverable

Change contents

• replacement in 0001-on at line 7
  [3.247]→[2.247:327](∅→∅)
  − -- on.code_change (runs after every time the driver sends a new definition)
  [3.247]

  [3.247]
  + -- on.code_change (runs after executing code received from the driver)