docs: point event_hooks at a caller-built httpx2 client (#149)

Author: lesnik512

docs/middleware.md

@@ -10,7 +10,7 @@ Middleware is for *cross-cutting* concerns — behavior that should apply to eve
 
 - **Per-call behavior that doesn't apply to other calls:** pass it through `request.extensions=` (or the `extensions=` kwarg at the call site) instead of a middleware.
 - **Instance state or two-sided inspection** (a counter, a CircuitBreaker's open/closed flag, timing that needs both the request and its response, or interleaving behavior around the `await next(...)` call): write a raw `AsyncMiddleware`/`Middleware` class rather than a phase decorator — decorators are a convenience for the cases where a single function suffices.
-- **Transform that doesn't need `httpware`'s exception mapping or chain ordering** (pure request/response side effects at the lowest level, including post-redirect hops): use `httpx2.event_hooks` on the wrapped `httpx2_client` instead. Phase decorators and middleware participate in the `httpware` chain (they see `httpware` exceptions and compose with `AsyncRetry`/`AsyncBulkhead`); `event_hooks` run a layer below, on every transport attempt.
+- **Transform that doesn't need `httpware`'s exception mapping or chain ordering** (pure request/response side effects at the lowest level, including post-redirect hops): use `event_hooks` on an `httpx2` client you build yourself and pass as `httpx2_client=`. Phase decorators and middleware participate in the `httpware` chain (they see `httpware` exceptions and compose with `AsyncRetry`/`AsyncBulkhead`); `event_hooks` run a layer below, on every transport attempt. That is also why `httpware` refuses `event_hooks=` as a client option: an `httpx2.HTTPStatusError` raised in a hook (say, by `raise_for_status()`) reaches the chain as a plain `TransportError` instead of a `StatusError`, so `AsyncRetry` never retries it and the circuit breaker never counts it.
 - **URL or header validation:** `httpx2` owns it — don't reimplement.
 - **HTTP-level span creation for tracing:** install `opentelemetry-instrumentation-httpx` instead of writing an OTel middleware in httpware. `opentelemetry-instrumentation-httpx` already covers transport-level tracing, so a separate httpware layer would duplicate it. See [Observability](observability.md).
 - **Redaction:** httpware redacts URLs before they reach logs, telemetry, and error messages — `user:pass@` userinfo is stripped and sensitive query- and fragment-parameter values are masked (`_internal/redaction.py`). It does **not** inspect or redact headers or request/response bodies, so if your own middleware logs those, redact them yourself (e.g. with a `logging.Filter`).