OpenAI Cookbook fixes broken image links in Deep Research API notebook

The commit edits two notebooks in the examples/deep_research_api directory: introduction_to_deep_research_api.ipynb and introduction_to_deep_research_api_agents.ipynb. The first changes the image path from ../../ ../ images/intro_dr.png (with a space) to ../../images/intro_dr.png, and the second fixes the reference path for agents_dr.png the same way, with one line changed per file. The original paths contained extra spaces and misplaced directory levels, so images would not display properly in the notebooks. For developers following the OpenAI Cookbook to learn the Deep Research API, this fix lets the example docs' diagrams load correctly, so readers can see the relevant illustrations when reading the rewriting_prompt and MCP server explanations. The commit was done by Claude Fable 5.1 and Konstantine Kahadze, and involves no changes to API interfaces, model capabilities, or call costs.