Aperture: Start making it REUSE compliant

TODO: Add licenses for app/libs/*

Test: pipx run reuse lint
Change-Id: Id66a572d9e11ed9da2c7a922c675c3176cc44c86
diff --git a/gradle.properties b/gradle.properties
index 3c7a8bd..8c38e4e 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: 2022-2023 The LineageOS Project
+# SPDX-License-Identifier: Apache-2.0
+
 # Project-wide Gradle settings.
 # IDE (e.g. Android Studio) users:
 # Gradle settings configured through the IDE *will override*