Added more details on the vts_config synopsis.
Bug: b/128337482
Test: Ran the doc generation command and verified that the synopsis
was updated in vts_config module.
Change-Id: I1d29a7f800b5dd4e6f1719af5d0d3b723202f33d
Test: internal (see android/vts_config_test.go) + run 'm vts' and check
that host/linux-x86/vts/android-vts.zip remians the same
Change-Id: I0249a974a240e7669c3b9378c17739df8e120873
Fixes: 122617100