issue #40: add docu to adjust game code

docs/howto_update_to_v1.md

@@ -35,4 +35,61 @@ Why is this a good thing?
 - Now the models get loaded early! Meaning that we have a structured object at hand instead of just a string.
 - Now we do not need to load all backends anymore at start! The `ModelSpec` carries the `backend` name to be later loaded.
 - Now you can provide a json-like string as the CLI `-m` option which carries additional information about the model. A minimal string would look like `{"model_name":"openchat", "backend":"openai_compatible"}`
-- Now we have a model registry that matches your given model spec with pre-defined ones. The first unifying one will be used.
+- Now we have a model registry that matches your given model spec with pre-defined ones. The first unifying one will be used.
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+
+## No more `compute_scores` in `GameMaster`, but in `GameScorer`
+
+The computation of the game scores is extracted from the game master to a separate game scorer class. 
+This further decouples game run logic from its later evaluation. Your game code must be adjusted as follows:
+
+```diff
+- from clemgame.clemgame import GameMaster, GameBenchmark
++ from clemgame.clemgame import GameMaster, GameBenchmark, GameScorer
+
+class ImageGameMaster(GameMaster):
+
+-     def compute_scores(self, episode_interactions: Dict) -> None:
+-         <your scoring code>
+
++ class ImageGameScorer(GameScorer):
++ 
++     def __init__(self, experiment: Dict, game_instance: Dict):
++         super().__init__(GAME_NAME, experiment, game_instance)
++         self.target_grid = game_instance["target_grid"] # necessary info to score the episode
+
++     def compute_scores(self, episode_interactions: Dict) -> None:
++         <your scoring code>
+    
+class ImageGameBenchmark(GameBenchmark):
+
++    def create_game_scorer(self, experiment: Dict, game_instance: Dict) -> GameScorer:
++        return ImageGameScorer(experiment, game_instance)
+```
+
+As you can see, the scorer will receive access to all necessary information to score an episode of the game.
+
+Alternatively, you can also directly migrate your code to use the `GameScorer` hooks as pre-defined in its `compute_scores` method:
+
+```python
+class GameScorer(GameResourceLocator):
+    
+    def __init__(self, name: str, experiment: dict, game_instance: dict):
+        super().__init__(name)
+        self.experiment = experiment
+        self.game_instance = game_instance
+        """ Stores values of score computation """
+        self.scores = {
+            "turn scores": {},
+            "episode scores": {},
+        }
+        
+    ...
+    
+    def compute_scores(self, episode_interactions: dict) -> None:
+        self.score_turns(episode_interactions)
+        self.score_game(episode_interactions)
+        
+    ...
+```
+
+Have a closer look at the `GameScorer` class for that.
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