update all the README.md about how to go to the desired project directory

[zjjzyl]

I've found the repository to be incredibly useful. However, upon walking throught the ai_customer_support_agent tutorials, it appears that the README.md files lack instructions on how to navigate to the project directory, which is essential for executing pip install -r requirements.txt successfully. To resolve this, I'm submitting a pull request to include the missing step.