Add tip on running order types for Bittrex

docs/faq.md

@@ -45,12 +45,24 @@ the tutorial [here|Testing-new-strategies-with-Hyperopt](bot-usage.md#hyperopt-c
 
 You can use the `/forcesell all` command from Telegram.
 
-### I get the message "RESTRICTED_MARKET"
+### I'm getting the "RESTRICTED_MARKET" message in the log
 
 Currently known to happen for US Bittrex users.  
 
 Read [the Bittrex section about restricted markets](exchanges.md#restricted-markets) for more information.
 
+### I'm getting the "Exchange Bittrex does not support market orders." message and cannot run my strategy
+
+As the message says, Bittrex does not support market orders and you have one of the [order types](configuration.md/#understand-order_types) set to "market". Probably your strategy was written for another exchanges in mind and sets "market" orders for "stoploss" orders, which is correct and preferable for most of other exchanges.
+
+To fix it for Bittrex, redefine order types in the configuration file (do this for all order types that are defined as "market" in your strategy):
+
+```
+"order_types": {
+    "stoploss": "limit",
+}
+```
+
 ### How do I search the bot logs for something?
 
 By default, the bot writes its log into stderr stream. This is implemented this way so that you can easily separate the bot's diagnostics messages from Backtesting, Edge and Hyperopt results, output from other various Freqtrade utility subcommands, as well as from the output of your custom `print()`'s you may have inserted into your strategy. So if you need to search the log messages with the grep utility, you need to redirect stderr to stdout and disregard stdout.