How to Change Python Package Index and Customize Library Installation When Deploying with Docker?

#### Description

When deploying the project using Docker, I would like to know:

1. How to change the Python package index (e.g., switch to a custom mirror or a local Python package index)?
2. How to add custom Python libraries or modify the existing dependencies?

It would be helpful if the documentation could include guidance or examples to achieve these configurations.

#### Expected Documentation Update or Solution

- Steps or instructions to specify a custom Python package index.
- A clear way to add custom libraries during Docker image build.

Review the project's Docker deployment documentation and image build configuration to identify where Python dependencies and package indexes are defined. Document how to use a custom Python package index and add or modify libraries, with examples that can be followed during the Docker image build.

Written by the indexing model from the issue text.