fix(docs): correct url_guard description to clarify DNS validation behaviour

The module table in the README now accurately describes that DNS validation returns addresses for callers to pin, rather than performing rebinding checks itself.

Auto-committed-on: dragonfly
Co-authored-by: Medulla <medulla@tinyhumans.ai>

Author: senamakel

crates/tinytools-std/README.md

@@ -5,7 +5,7 @@ Host-independent building blocks for agent tools, extracted from OpenHuman.
 | Module | What it is |
 | --- | --- |
 | `file_state` | Process-wide read/write stamps so parallel agents detect stale or partial reads before overwriting a file. The host decides whether the guard is on (`init_global(enabled)`). |
-| `url_guard` | URL validation with SSRF and DNS-rebinding checks for outbound network tools. |
+| `url_guard` | URL validation with SSRF checks; DNS validation returns addresses callers must pin for the connection. |
 | `detect_tools` | `find_on_path` and the read-only `detect_tools` tool. |
 
 No enforcement of host policy lives here; the crate only supplies mechanisms.