Merge "improve the TelecomManager#addCall docs" into udc-dev am: 04d8f589eb am: 01c1f0ee50

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22263250

Change-Id: I864bc24c1b123baf9c98c61231e542cfab4dad32
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>