Changed max_open_trades default range for optimization

docs/advanced-hyperopt.md

@@ -127,7 +127,7 @@ class MyAwesomeStrategy(IStrategy):
         # Define a custom max_open_trades space
         def trades_space(self) -> List[Dimension]:
             return [
-                Integer(1, 10, name='max_open_trades'),
+                Integer(-1, 10, name='max_open_trades'),
             ]
 ```
 

freqtrade/optimize/hyperopt_interface.py

@@ -198,7 +198,7 @@ class IHyperOpt(ABC):
         You may override it in your custom Hyperopt class.
         """
         return [
-            Integer(1, 10, name='max_open_trades'),
+            Integer(-1, 10, name='max_open_trades'),
         ]
 
     # This is needed for proper unpickling the class attribute timeframe