Clarify `adb sync -l` help text.

Seems like the bug submitter thought that -l listed the partitions shown
on the line above, rather than the files. Be more explicit.

Bug: https://issuetracker.google.com/73122762
Test: treehugger
Change-Id: I6ed1027639a5b785a5992909430d739958d10ad7
1 file changed