[DOCS] document how to obtain cache stats when caching system prompt #118
Description
Documentation Section
Current State
We should document on https://strandsagents.com/latest/user-guide/concepts/model-providers/amazon-bedrock/#system-prompt-caching how to get the cache stats. Currently the page does not have those details.
Suggested Improvement
CacheReadInputTokens and CacheWriteInputTokens in https://docs.aws.amazon.com/bedrock/latest/userguide/prompt-caching.html have this info. It is available in the event event type in Strands async iterators and callback handlers, for example: https://github.com/strands-agents/sdk-python/blob/1421aadd73c7a497503e43864649c9016dadea69/tests-integ/test_bedrock_cache_point.py#L21-L27
Documentations improvements: getting info on them should be documented in https://strandsagents.com/latest/user-guide/concepts/model-providers/amazon-bedrock/#system-prompt-caching
Another possible improvement is to return this info as a part of AgentResult.metrics and OpenTelemetry traces. That way, one does not need to write async handlers to get at this info.
Rationale
better documentation and ease of use
Additional Context
No response