add missing doc-strings for tree-manager mandatory labels settings

backend/oasst_backend/config.py

@@ -47,8 +47,13 @@ class TreeManagerConfiguration(BaseModel):
     """Number of rankings in which the message participated."""
 
     mandatory_labels_initial_prompt: Optional[list[protocol_schema.TextLabel]] = [protocol_schema.TextLabel.spam]
+    """Mandatory labels in text-labeling tasks for initial prompts."""
+
     mandatory_labels_assistant_reply: Optional[list[protocol_schema.TextLabel]] = [protocol_schema.TextLabel.spam]
+    """Mandatory labels in text-labeling tasks for assistant reylies."""
+
     mandatory_labels_prompter_reply: Optional[list[protocol_schema.TextLabel]] = [protocol_schema.TextLabel.spam]
+    """Mandatory labels in text-labeling tasks for prompter replies."""
 
 
 class Settings(BaseSettings):

backend/oasst_backend/tree_manager.py

@@ -68,9 +68,11 @@ class IncompleteRankingsRow(pydantic.BaseModel):
 class TreeManager:
     _all_text_labels = list(map(lambda x: x.value, protocol_schema.TextLabel))
 
-    def __init__(self, db: Session, prompt_repository: PromptRepository):
+    def __init__(
+        self, db: Session, prompt_repository: PromptRepository, cfg: Optional[TreeManagerConfiguration] = None
+    ):
         self.db = db
-        self.cfg = settings.tree_manager
+        self.cfg = cfg or settings.tree_manager
         self.pr = prompt_repository
 
     def _task_selection(