message: Update reference topics
diff: @@ -14,13 +14,17 @@ Topics might include:
  - introduction
  - elimination
  - sequences
  - - lists
  - - arrays
  - literals
  - numbers
  - strings
  - characters
  - builtin types
  + - floating point
  + - signed/unsigned integers
  + - strings
  + - characters
  + - lists
  + - arrays
  - universes
  - cumulativity
  - lifting operator
  