Add e2e test coverage explanation to remediation

Author: ryan-crabbe

docs/my-website/blog/httpx_cache_eviction_incident/index.md

@@ -128,3 +128,5 @@ The other improvements from PR #21717 were kept:
 | Remove `_remove_key` override that closes shared clients on eviction | ✅ Done | [PR #22247](https://github.com/BerriAI/litellm/pull/22247) |
 | Add e2e test: evicted client still usable (capacity) | ✅ Done | [PR #22313](https://github.com/BerriAI/litellm/pull/22313) |
 | Add e2e test: expired client still usable (TTL) | ✅ Done | [PR #22313](https://github.com/BerriAI/litellm/pull/22313) |
+
+The e2e tests go through `get_async_httpx_client()` the same code path the proxy uses in production and assert the client is still functional after eviction. These run in CI on every PR against `main`. If anyone modifies `LLMClientCache` eviction behavior, overrides `_remove_key`, or adds any form of client cleanup on eviction, these tests will fail regardless of the implementation approach.