Remove recommendation of busybox

This is to prevent weird behaviors.

README.md

@@ -310,8 +310,6 @@ Undocumented system binaries are all bundled and executable:
 * `sh`;
 * `su`.
 
-If some of these are unavailable, you can alternatively install a recent version (v1.28.1 or higher) of Busybox.
-
 Wi-Fi driver `wpa_supplicant`:
 
 * P2P configuration file is assumed to be saved to [`/data/vendor/wifi/wpa/p2p_supplicant.conf` or `/data/misc/wifi/p2p_supplicant.conf`](https://android.googlesource.com/platform/external/wpa_supplicant_8/+/0b4856b6dc451e290f1f64f6af17e010be78c073/wpa_supplicant/hidl/1.1/supplicant.cpp#26) and have reasonable format;