docs: add documentation for BNFCR futures

Author: xmatthias

docs/exchanges.md

@@ -118,7 +118,7 @@ When trading on Binance Futures market, orderbook must be used because there is
   },
 ```
 
-#### Binance futures settings
+#### Binance isolated futures settings
 
 Users will also have to have the futures-setting "Position Mode" set to "One-way Mode", and "Asset Mode" set to "Single-Asset Mode".
 These settings will be checked on startup, and freqtrade will show an error if this setting is wrong.
@@ -127,6 +127,27 @@ These settings will be checked on startup, and freqtrade will show an error if t
 
 Freqtrade will not attempt to change these settings.
 
+#### Binance BNFCR futures
+
+BNFCR mode are a special type of futures mode on Binance to work around regulatory issues in Europe.  
+To use BNFCR futures, you will have to have the following combination of settings:
+
+``` jsonc
+{
+    // ...
+    "trading_mode": "futures",
+    "margin_mode": "cross",
+    "proxy_coin": "BNFCR",
+    "stake_currency": "USDT" // or "USDC"
+    // ...
+}
+```
+
+the `stake_currency` setting defines the markets the bot will be operating in. This choice is really arbitrary.
+
+On the exchange, you'll have to use "Multi-asset Mode" - and "Position Mode set to "One-way Mode".
+Freqtrade will check these settings on startup, but won't attempt to change them.
+
 ## Bingx
 
 BingX supports [time_in_force](configuration.md#understand-order_time_in_force) with settings "GTC" (good till cancelled), "IOC" (immediate-or-cancel) and "PO" (Post only) settings.

docs/leverage.md

@@ -82,7 +82,7 @@ Each market(trading pair), keeps collateral in a separate account
 "margin_mode": "isolated"
 ```
 
-#### Cross margin mode (currently unavailable)
+#### Cross margin mode
 
 One account is used to share collateral between markets (trading pairs). Margin is taken from total account balance to avoid liquidation when needed.