Merge "JUnit readme displays updated apk file location"

To build the tests you can use the following command at the root of your android source tree

$ make SettingsUnitTests

The test apk then needs to be installed onto your test device via for example

$ adb install -r out/target/product/shamu/data/app/SettingsUnitTests/SettingsUnitTests.apk

The test apk then needs to be installed onto your test device. The apk's location will vary

depending on your device model and architecture. At the end of the make command's output, there

should be a line similar to the following:

"Copy: out/target/product/shamu/testcases/SettingsUnitTests/arm64/SettingsUnitTests.apk"

Install via the following command:

$ adb install -r out/target/product/shamu/testcases/SettingsUnitTests/arm64/SettingsUnitTests.apk

To run all tests:

$ adb shell am instrument -w com.android.settings.tests.unit/androidx.test.runner.AndroidJUnitRunner