message: Clarify how data is consumed during parsing
diff: @@ -403,7 +403,8 @@ representation of the referenced format.
  ### Succeed format
  -The succeed format allows values to be embedded in the resulting parsed output.
  +The succeed format consumes no input during parsing, allowing values to be
  +embedded in the resulting parsed output.
  - `succeed : fun (A : Type) -> A -> Format`
  @@ -430,8 +431,9 @@ The fail format should never produce a term, so is represented with [void](#void
  ### Unwrap format
  -An unwrap format succeeds with the data contained in a the `some` case of an
  -[option](#options), or fails.
  +The unwrap format consumes no input during parsing, succeeding with the data
  +contained in a the `some` case of an [option](#options), or otherwise causing a
  +parse failure.
  - `unwrap : fun (A : Type) -> Option A -> Format`
  