add resume support to dwl

README.md

@@ -240,6 +240,7 @@ change the default without having to pass flags every time.
 | Key | Default | Description |
 |---|---|---|
 | `DWL_PREFERRED_TOOL` | _(empty)_ | Force `dwl` to use `curl`, `wget`, or `fetch` (auto-detected when unset) |
+| `DWL_DEFAULT_RESUME` | `0` | Enable `dwl` resume mode by default (`1`/`true`/`yes`/`on`); applies to file downloads |
 | `MYEXTIP_DEFAULT_URL` | `https://ip-api.com/json` | API endpoint used by `myextip` |
 
 **`[packages]`**