Update identity commit requirements in documentation

Clarified identity commit requirements for RBU regarding usage cues and pack keys.

Author: CuriousOne23

thought_simulator/requirements_20/20.51_rbu_prim.md

@@ -96,7 +96,7 @@ New HLRs begin at **HLR‑20.051‑017**.
 ## **4.1 Meaning‑Side Commit Requirements**
 
 ### **HLR‑20.051‑001 — Identity Commit**  
-RBU SHALL commit identity cues (subculture, persona, role) into `TP.semantic.identity` based on IdOB output.
+RBU SHALL commit identity cues (subculture, persona, role) into `TP.semantic.identity` based on IdOB output.**RBU SHALL commit identity cues (subculture, persona, role) as usage cues, not pack keys, into TP.semantic.identity based on IdOB output.
 
 ### **HLR‑20.051‑002 — Stance/Register/Tone Commit**  
 RBU SHALL commit stance, register, and tone into: