adjust default logLevel configuration

Sources/SwiftGraphQLClient/Client/Config.swift

@@ -7,5 +7,8 @@ public class ClientConfiguration {
     /// Logger that we use to communitcate state changes and events inside the client.
     open var logger: Logger = Logger(label: "graphql.client")
 
-    public init() {}
+    public init() {
+        // Certain built-in exchanges (e.g. `DebugExchange`) product `.debug` logs that require `.debug` log level to be visible. This makes sure that the expected functionality of all exchanges matches the actual functionality (e.g. "debug exchange actually prints messages in the console").
+        self.logger.logLevel = .debug
+    }
 }

Sources/SwiftGraphQLClient/Exchanges/DebugExchange.swift

@@ -3,6 +3,16 @@ import Foundation
 import GraphQL
 
 /// Exchange that logs operations going down- and results going up-stream.
+///
+/// - NOTE: `DebugExchange` assumes that the logger level of the client is set to `.debug`. Otherwise, the logs might not appear in the stream.
+///
+/// ```swift
+/// // chaning the client logger level
+/// var config = SwiftGraphQLClient.ClientConfiguration()
+/// config.logger.logLevel = .debug
+///
+/// SwiftGraphQLClient.Client(request: request, exchanges: exchanges, config: config)
+/// ```
 public struct DebugExchange: Exchange {
 
     /// Tells whether the client is in a development environment of not.