Finetune a comment

Author: joehsieh

Sources/SKCore/FileBuildSettings.swift

@@ -25,7 +25,7 @@ public struct FileBuildSettings: Equatable {
   /// The working directory to resolve any relative paths in `compilerArguments`.
   public var workingDirectory: String? = nil
 
-  /// The isFallback to know if the fileBuildSetting is specified or the default one.
+  /// Whether the build settings were computed from a real build system or whether they are synthesized fallback arguments while the build system is still busy computing build settings.
   public var isFallback: Bool
 
   public init(compilerArguments: [String], workingDirectory: String? = nil, isFallback: Bool = false) {