Make a tutorial (starter guide) how to use RAGU

[AsphodelRem]

Create comprehensive documentation for RAGU that includes:

• An overview of the RAGU API.
• A description of all available extractors and recommendations on when to use each one.
• A description of all search engines and their intended use cases.
• Cost and latency estimates for each major component.
• A comparison of components in terms of quality, speed, cost and resource requirements
• Provide a guide on configuring and running local inference models for use with RAGU, including supported backends, required settings, and example configurations.