Comments about btstack_run_loop_execute (#388)

Co-authored-by: Graham Sanderson <graham.sanderson@raspberrypi.com>

pico_w/bt/standalone/client.c

@@ -272,6 +272,20 @@ int main() {
     // turn on!
     hci_power_control(HCI_POWER_ON);
 
+    // btstack_run_loop_execute is only required when using the 'polling' method (e.g. using pico_cyw43_arch_poll library).
+    // This example uses the 'threadsafe background` method, where BT work is handled in a low priority IRQ, so it
+    // is fine to call bt_stack_run_loop_execute() but equally you can continue executing user code.
+
+#if 1 // this is only necessary when using polling (which we aren't, but we're showing it is still safe to call in this case)
     btstack_run_loop_execute();
+#else
+    // this core is free to do it's own stuff except when using 'polling' method (in which case you should use 
+    // btstacK_run_loop_ methods to add work to the run loop.
+
+    // this is a forever loop in place of where user code would go.
+    while(true) {      
+        sleep_ms(1000);
+    }
+#endif
     return 0;
 }