Update user documentation: describe sequential LLM calls for moderation, correctness, and feedback, and clarify context/answer fields

Author: m-messer

docs/user.md

@@ -1,3 +1,9 @@
-# YourFunctionName
+# LLM Caller
 
-Teacher-facing documentation for this function.
+Makes up to three calls to the nominated LLM:
+
+- **Moderation prompt** (standalone) → returns a `passes_moderation` Boolean. If false, evaluation stops here and skips the two calls below.
+- **Main prompt (`correctness_decision`)** + built-in JSON-output instruction → returns an `is_correct` Boolean
+- **Main prompt (`correctness_decision`)** + **feedback prompt (`feedback_guidance`)**, told the correctness verdict → returns a `feedback` string
+
+The `{{answer}}` field comes from the task's reference solution (the configure panel's `answer`). The `{{context}}` field is not automatically populated but can be added as a parameter, or just included directly in the prompt.