docs(bedrock): clarify inference profile model IDs

[wilyan09007]

Summary:
Fixes #894 by clarifying that some Bedrock models require an inference profile ID or ARN instead of a bare model ID. The example now uses an inference profile ID by default.

Changes:

• Add guidance for inference profile IDs and ARNs.
• Change the example model value to an inference profile ID.
• Reuse the documented model constant in both example calls.

Testing instructions:

• Run uv run ruff format --check examples\bedrock.py.
• Run uv run ruff check examples\bedrock.py.
• Run uv run --all-extras pytest tests\lib\test_bedrock.py -n0 -k "messages_retries or application_inference_profile or api_key_auth".
• Confirm the example shows an inference profile ID.