Adding AWS Bedrock as option

[erdoganhalit]

I added the necessary settings to be able to use AWS Bedrock models with PrivateGPT with the necessary explanations in the descriptions.md file.

[lopagela]

Looks like this work has been made on an old version of privateGPT -- please do a git pull --rebase upstream main.

Converting this back to draft, while @erdoganhalit re-sync this branch with main, and also make the CICD tests pass (make check and make test locally)

[github-actions[bot]]

Published docs preview URL: https://privategpt-preview-eb1b22ef-e099-4790-b449-af5e9c8626fb.docs.buildwithfern.com

[imartinez]

Could you please adapt it to the latest version of PrivateGPT? Thanks!