Update the command to enable the VM launcher activity.

It should use alias after aosp/3133394

Change-Id: Ic75d6ef30c3a13612ce206be9057a0dcae238bd2
diff --git a/docs/custom_vm.md b/docs/custom_vm.md
index 1e15d16..534a45b 100644
--- a/docs/custom_vm.md
+++ b/docs/custom_vm.md
@@ -210,7 +210,7 @@
 
 ```
 $ adb root
-$ adb shell pm enable com.android.virtualization.vmlauncher/.MainActivity
+$ adb shell pm enable com.android.virtualization.vmlauncher/.MainActivityAlias
 $ adb unroot
 ```
 
@@ -218,7 +218,7 @@
 permission to the app.
 ```
 $ adb root
-$ adb shell pm enable com.google.android.virtualization.vmlauncher/com.android.virtualization.vmlauncher.MainActivity
+$ adb shell pm enable com.google.android.virtualization.vmlauncher/com.android.virtualization.vmlauncher.MainActivityAlias
 $ adb shell pm grant com.google.android.virtualization.vmlauncher android.permission.USE_CUSTOM_VIRTUAL_MACHINE
 $ adb unroot
 ```