Update README.md to include AWS Bedrock Details

[egrosdou01]

Since release v1.19.1 supports AWS Bedrock with PR #1045, the README.md should reflect the changes.

• export AWS_BEARER_TOKEN_BEDROCK="Token"

I can work on this issue.

[dgageot]

Thanks @egrosdou01, I assigned you!

[dgageot]

Done with #1385