Change key (#2) (#3)

README.md

@@ -44,7 +44,7 @@ Your events will now begin to flow to Survicate in device mode.
 
 ***identify***
 
-In the SurvicateDestination plugin, the identify event from Segment is transferred to the setUserTrait method of Survicate. This is achieved within the identify function of the SurvicateDestination class. The traits and userId from the IdentifyEvent are extracted and set as user traits in Survicate using the setUserTrait method. The traits are a dictionary where each key-value pair is set as a user trait. The userId is also set as a user trait with the key "userId".
+In the SurvicateDestination plugin, the identify event from Segment is transferred to the setUserTrait method of Survicate. This is achieved within the identify function of the SurvicateDestination class. The traits and userId from the IdentifyEvent are extracted and set as user traits in Survicate using the setUserTrait method. The traits are a dictionary where each key-value pair is set as a user trait. The user Id is also set as a user trait with the key "user_id".
 
 ***track***
 
@@ -56,4 +56,4 @@ Similarly, the screen method from Segment is used as the enterScreen method in S
 
 ***reset***
 
-The reset method from Segment is used as the reset method in Survicate. This means that when you reset the user in Segment, it will be reset in Survicate.
+The reset method from Segment is used as the reset method in Survicate. This means that when you reset the user in Segment, it will be reset in Survicate.

Sources/SurvicateDestination/SurvicateDestination.swift

@@ -32,7 +32,7 @@ public class SurvicateDestination: DestinationPlugin {
 
     public func identify(event: IdentifyEvent) -> IdentifyEvent? {       
         if let userId = event.userId {
-            SurvicateSdk.shared.setUserTrait(withName: "userId", value: userId)
+            SurvicateSdk.shared.setUserTrait(withName: "user_id", value: userId)
         }
 
         if let traits = event.traits?.dictionaryValue {