lowercase another sneaky capital P (#2032)

Author: Lupie

examples/gpt-5/gpt-5_prompting_guide.ipynb

@@ -80,7 +80,7 @@
     "\n",
     "Generally, it can be helpful to clearly state the stop conditions of the agentic tasks, outline safe versus unsafe actions, and define when, if ever, it’s acceptable for the model to hand back to the user. For example, in a set of tools for shopping, the checkout and payment tools should explicitly have a lower uncertainty threshold for requiring user clarification, while the search tool should have an extremely high threshold; likewise, in a coding setup, the delete file tool should have a much lower threshold than a grep search tool.\n",
     "\n",
-    "### Tool Preambles\n",
+    "### Tool preambles\n",
     "We recognize that on agentic trajectories monitored by users, intermittent model updates on what it’s doing with its tool calls and why can provide for a much better interactive user experience - the longer the rollout, the bigger the difference these updates make. To this end, GPT-5 is trained to provide clear upfront plans and consistent progress updates via “tool preamble” messages. \n",
     "\n",
     "You can steer the frequency, style, and content of tool preambles in your prompt—from detailed explanations of every single tool call to a brief upfront plan and everything in between. This is an example of a high-quality preamble prompt:\n",