profile: Add comment about fallback profile usage.
resource: change functionality.

Resource plugin looks for media.* properties in request proplist.
1) if no media.* is found in proplist, default for ENABLED for all
sinks.
2) if media.foo is found in proplist, default for DISABLED for all
sinks, and enable only those specifically enabled in proplist.
Merge branch 'dev' of https://github.com/jusa/ngfd