Update Documentation for new confirm_trade_exit behavior

docs/backtesting.md

@@ -530,8 +530,9 @@ Since backtesting lacks some detailed information about what happens within a ca
 - Exit-reason does not explain if a trade was positive or negative, just what triggered the exit (this can look odd if negative ROI values are used)
 - Evaluation sequence (if multiple signals happen on the same candle)
   - Exit-signal
-  - ROI (if not stoploss)
   - Stoploss
+  - ROI
+  - Trailing stoploss
 
 Taking these assumptions, backtesting tries to mirror real trading as closely as possible. However, backtesting will **never** replace running a strategy in dry-run mode.
 Also, keep in mind that past results don't guarantee future success.

docs/strategy-callbacks.md

@@ -563,6 +563,14 @@ class AwesomeStrategy(IStrategy):
 
 `confirm_trade_exit()` can be used to abort a trade exit (sell) at the latest second (maybe because the price is not what we expect).
 
+`confirm_trade_exit()` may be called multiple times within one iteration for the same trade if different exit-reasons apply.
+The exit-reasons (if applicable) will be in the following sequence:
+
+* `exit_signal` / `custom_exit`
+* `stop_loss`
+* `roi`
+* `trailing_stop_loss`
+
 ``` python
 from freqtrade.persistence import Trade
 
@@ -605,6 +613,9 @@ class AwesomeStrategy(IStrategy):
 
 ```
 
+!!! Warning
+    `confirm_trade_exit()` can prevent stoploss exits, causing significant losses as this would ignore stoploss exits.
+
 ## Adjust trade position
 
 The `position_adjustment_enable` strategy property enables the usage of `adjust_trade_position()` callback in the strategy.