docs: Update function name from AWSBedrockCohereStream to AWSBedrockLlama2Stream 🌱

[agustints]

Summary:

This pull request updates the function name in the documentation from AWSBedrockCohereStream to AWSBedrockLlama2Stream.

Changes Made:

Corrected function name in the documentation to reflect AWSBedrockLlama2Stream.

Context:

The modification addresses an issue where the documentation had an incorrect function name, which was copied from a previous example. The accurate function name, AWSBedrockLlama2Stream, has now been incorporated into the documentation. This adjustment ensures that the documentation aligns with the correct implementation, enhancing clarity and preventing potential confusion for users relying on the provided examples.

[MaxLeiter]

thanks!