Add documentation for ACTION_MULTI_SIM_CONFIG_CHANGED

Bug: 143652732
Test: build
Change-Id: Id27e6edc82a48ece4a94c8bc7aadbc5e1acf08d7
Merged-In: Id27e6edc82a48ece4a94c8bc7aadbc5e1acf08d7
1 file changed