Add some more documentation

Author: Val Brodsky

libs/labelbox/src/labelbox/schema/tool_building/fact_checking_tool.py

@@ -77,6 +77,8 @@ class NoFactualInformationStepActions(Enum):
 class FactCheckingTool(_BaseStepReasoningTool):
     """
     Use this class in OntologyBuilder to create a tool for fact checking
+
+    Note variant kinds can not be changed
     """
 
     type: ToolType = field(default=ToolType.FACT_CHECKING, init=False)