add missing expectation, instructions updates

Author: atk

exercises/jigsaw-puzzle/canonical-data.json

@@ -98,6 +98,9 @@
         "rows": "100",
         "columns": "1000",
         "format": "square"
+      },
+      "expected": {
+        "error": "Contradictory data"
       }
     },
     {

exercises/jigsaw-puzzle/instructions.md

@@ -8,12 +8,13 @@ The full information about the jigsaw puzzle contains the following parts:
 - `rows`: Number of rows of pieces
 - `columns`: Number of columns of pieces
 - `aspectRatio`: Aspect ratio of columns / rows
-- `format`: Format of the puzzle: `"portrait" / "square" / "landscape" / "globe"`
+- `format`: Puzzle format, which can be `portrait`, `square`, `landscape`, or `globe`
 
-For the rows and columns of a puzzle globe, assume an aspect ratio of 1.0, so that rows and columns are identical.
+For a puzzle in `globe` format, assume an aspect ratio of 1.0.
 
 Spoilt by the comfort of your helper, your friend now no longer wants to count border pieces.
-To help with estimating, you take the number of pieces and return an array of the possible numbers of rows and columns.
+To help with estimating, you take the number of pieces and return a list of the possible numbers of rows and columns.
 
 Start with the lowest number of rows and work your way up from there.
 While a single-row jigsaw puzzle might be a strange novelty, it is theoretically possible, so you should include this case.
+

exercises/jigsaw-puzzle/introduction.md

@@ -1 +1,5 @@
-Your best friend started to collect puzzles. A catalogue the collection should contain as much information as possible. After solving one of the puzzles to count the rows, columns, amount of border and inside pieces, you are tasked to provide some helper functions.
+# Introduction
+
+Your best friend has started collecting jigsaw puzzles and wants to build a detailed catalogue for the collection — recording information like the number of pieces, rows, columns, border pieces, inside pieces, aspect ratio, and the puzzle's format.
+After solving one of the puzzles to figure out these details, you're now helping fill in the gaps for others in the collection, even when some data is missing.
+