add docs on calling bedrock via openai proxy (LiteLLM) - supports vision/tool calling/embeddings/image gen

[krrishdholakia]

*Issue n/a

Description of changes:

Adds a doc on calling bedrock via litellm proxy. This allows bedrock models to be called via an openai-compatible endpoint.

cc: @jpil-builder @mttanke @DanyStinson

[rsgrewal-aws]

Please re do this PR following the new layout and the process for creating the required file . We request all files to have a presence on the Cookbook / Recipes Website which is fronting this github repo now. Some of the mandatory sections of the notebook need to include

• Overview.
• What are we demonstrating .
• What use case .
• What will you learn.
• What is the architectural pattern and why we select this. With a diagram
• What are the libraries to install
• What model did we choose and why this model
• Every cell needs to have a markup