Clarify comment how manifests are combined.

ODM manifest pieces augment the core manifest. Only when the old odm
manifest location is used does an override happen. This is covered by
items (3) and (4) in the doc this CL edits.

Change-Id: I8d5cd60a65d57210fa744e02106601da50573efe
Fixes: 117533120
Test: N/A
1 file changed