doc: update sync configuration doc

doc/configuration/sync.md

@@ -1,17 +1,26 @@
 # Sync Private Trading Data
 
-You can use the following configuration (add this to your bbgo.yaml) to sync your private trading data, like closed orders and trades:
+You can use the following configuration (add this to your bbgo.yaml) to sync your private trading data, like closed
+orders and trades:
 
 ```yaml
 sync:
   # since is the date you want to start sync
   since: 2019-11-01
-  
+
   # if you have multiple sessions defined, but you don't want to sync all sessions, you can define a list here
   sessions:
   - binance
   - max
-  
+
+  # optional, if you want to insert the trades and orders from the websocket stream
+  # if you're running multiple bbgo instance, you should avoid setting this on
+  userDataStream:
+    # if you set this, all received trades will be written into the database
+    trades: true
+    # if you set this, all received filled orders will be written into the database
+    filledOrders: true
+
   # symbols is the symbol you want to sync
   # If not defined, BBGO will try to guess your symbols by your existing account balances
   symbols:

pkg/bbgo/environment.go

@@ -476,6 +476,7 @@ func (environ *Environment) BindSync(userConfig *Config) {
 	}
 
 	for _, session := range environ.sessions {
+		// if trade sync is on, we will write all received trades
 		if userConfig.Sync.UserDataStream.Trades {
 			session.UserDataStream.OnTradeUpdate(tradeWriter)
 		}