Make Fingerprint Virtual HAL APEX as default

- moved apex definition beside the HAL binary definition
- updated README.md about installation

Bug: 306314086
Test: follow README.md to test the virtual FP HAL
Change-Id: I4bb2572ca79c93cb32a273625f4e965c2505e48a
diff --git a/biometrics/fingerprint/aidl/default/fingerprint-example.rc b/biometrics/fingerprint/aidl/default/fingerprint-example.rc
index ee4713c..da4ea45 100644
--- a/biometrics/fingerprint/aidl/default/fingerprint-example.rc
+++ b/biometrics/fingerprint/aidl/default/fingerprint-example.rc
@@ -1,4 +1,4 @@
-service vendor.fingerprint-example /vendor/bin/hw/android.hardware.biometrics.fingerprint-service.example
+service vendor.fingerprint-example /apex/com.android.hardware.biometrics.fingerprint.virtual/bin/hw/android.hardware.biometrics.fingerprint-service.example
     class hal
     user nobody
     group nobody