clarify comment on usage of UnsafeTransfer

Author: sebsto

Plugins/AWSLambdaPackager/PluginUtils.swift

@@ -35,9 +35,10 @@ struct Utils {
         defer { fclose(stdout) }
 
         // We need to use an unsafe transfer here to get the fd into our Sendable closure.
-        // This transfer is fine, because we guarantee that the code in the outputHandler
-        // is run before we continue the functions execution, where the fd is used again.
-        // See `process.waitUntilExit()` and the following `outputSync.wait()`
+        // This transfer is fine, because we write to the variable from a single SerialDispatchQueue here.
+        // We wait until the process is run below process.waitUntilExit().
+        // This means no further writes to output will happen.
+        // This makes it save for us to read the output
         struct UnsafeTransfer<Value>: @unchecked Sendable {
             let value: Value
         }