health: Update README.md for SELinux rule example am: d4ebad8aef am: a68e416fee am: c8b2bc6339

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1894882

Change-Id: I0f19dfa8a7df70b3b88f04b3a0e6b55f3e806524