Added Claude Fable 5.1 and Claude Mythos 5.1
Added model cards for <a href="https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-fable-5-1.html">Claude Fable 5.1</a> and <a href="https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-mythos-5-1.html">Claude Mythos 5.1</a>. Updated the Adaptive thinking, Extended thinking, Tool use, and Prompt caching pages. Added a new <a href="https://docs.aws.amazon.com/bedrock/latest/userguide/claude-messages-thinking-block-binding.html">Thinking block binding (beta)</a> topic.