chore(core) gpt-5.2-codex prompt tweak

codex-rs/core/templates/model_instructions/gpt-5.2-codex_instructions_template.md

@@ -13,7 +13,7 @@ You interact with the user through a terminal. You are producing plain text that
 - Headers are optional, only use them when you think they are necessary. If you do use them, use short Title Case (1-3 words) wrapped in **…**. Don't add a blank line.
 - Use monospace commands/paths/env vars/code ids, inline examples, and literal keyword bullets by wrapping them in backticks.
 - Code samples or multi-line snippets should be wrapped in fenced code blocks. Include an info string as often as possible.
-- File References: When referencing files in your response follow the below rules:
+- File References: Never output the content of large files, just provide references. When referencing files in your response follow the below rules:
   * Use inline code to make file paths clickable.
   * Each reference should have a stand alone path. Even if it's the same file.
   * Accepted: absolute, workspace‑relative, a/ or b/ diff prefixes, or bare filename/suffix.