Rework etl documentation (#2250)

* Rework etl documentation

This PR is part of our project of making our Practice Exercises
more consistent and human. For more context please see the
following forum-thread:
https://forum.exercism.org/t/new-project-making-practice-exercises-more-consistent-and-human-across-exercism/3943

The main change is to use a made-up game instead of Scrabble,
and use localization as the pretext for the story.

* Update exercises/etl/metadata.toml

Author: kytrinyx

exercises/etl/canonical-data.json

@@ -1,7 +1,7 @@
 {
   "exercise": "etl",
   "comments": [
-    "Transforms a set of legacy Scrabble data stored as letters per score",
+    "Transforms a set of legacy Lexiconia data stored as letters per score",
     "to a set of data stored score per letter.",
     "Note:  The expected input data for these tests should have",
     "integer keys (not stringified numbers as shown in the JSON below",

exercises/etl/description.md

@@ -0,0 +1,27 @@
+# Instructions
+
+Your task is to change the data format of letters and their point values in the game.
+
+Currently, letters are stored in groups based on their score, in a one-to-many mapping.
+
+- 1 point: "A", "E", "I", "O", "U", "L", "N", "R", "S", "T",
+- 2 points: "D", "G",
+- 3 points: "B", "C", "M", "P",
+- 4 points: "F", "H", "V", "W", "Y",
+- 5 points: "K",
+- 8 points: "J", "X",
+- 10 points: "Q", "Z",
+
+This needs to be changed to store each individual letter with its score in a one-to-one mapping.
+
+- "a" is worth 1 point.
+- "b" is worth 3 points.
+- "c" is worth 3 points.
+- "d" is worth 2 points.
+- etc.
+
+As part of this change, the team has also decided to change the letters to be lower-case rather than upper-case.
+
+~~~~exercism/note
+If you want to look at how the data was previously structured and how it needs to change, take a look at the examples in the test suite.
+~~~~

exercises/etl/instructions.md

@@ -0,0 +1,16 @@
+# Introduction
+
+You work for a company that makes an online multiplayer game called Lexiconia.
+
+To play the game, each player is given 13 letters, which they must rearrange to create words.
+Different letters have different point values, since it's easier to create words with some letters than others.
+
+The game was originally launched in English, but it is very popular, and now the company wants to expand to other languages as well.
+
+Different languages need to support different point values for letters.
+The point values are determined by how often letters are used, compared to other letters in that language.
+
+For example, the letter 'C' is quite common in English, and is only worth 3 points.
+But in Norwegian it's a very rare letter, and is worth 10 points.
+
+To make it easier to add new languages, your team needs to change the way letters and their point values are stored in the game.

exercises/etl/introduction.md

@@ -1,4 +1,4 @@
 title = "ETL"
-blurb = "We are going to do the `Transform` step of an Extract-Transform-Load."
-source = "Exercise by the JumpstartLab team for students at The Turing School of Software and Design."
+blurb = "Change the data format for scoring a game to more easily add other languages."
+source = "Based on an exercise by the JumpstartLab team for students at The Turing School of Software and Design."
 source_url = "https://turing.edu"