Emergency alert settings UX improvement

Put better description for DnD overriding
and alert reminder. Easier for end user
to understand.

Test: Manual
Bug: 147426188
Merged-In: Ic1dc5f307fddd1f3be650c91952f9cf8d3854f69
Change-Id: Ic1dc5f307fddd1f3be650c91952f9cf8d3854f69
(cherry picked from commit b81a7138fed1ce056a2ffc6ac4f26d0747e50f8d)
2 files changed