docs: add missing README for usb-logger

embassy-usb-logger/README.md

@@ -0,0 +1,15 @@
+# embassy-usb-logger
+
+USB implementation of the `log` crate. This logger can be used by any device that implements `embassy-usb`. When running,
+it will output all logging done through the `log` facade to the USB serial peripheral.
+
+## Usage
+
+Add the following embassy task to your application. The `Driver` type is different depending on which HAL you use.
+
+ ```rust
+#[embassy_executor::task]
+async fn logger_task(driver: Driver<'static, USB>) {
+    embassy_usb_logger::run!(1024, log::LevelFilter::Info, driver);
+}
+```