Align discovery ownership and contributor documentation

docs/consumers/README.md

@@ -55,6 +55,21 @@ both without redefining their syntax. ConfigKit overlays are configuration overl
 they do not select or replace an application's LLM, model, pipeline, report, or
 execution profile concepts.
 
+## Explicit main-file discovery
+
+Applications choose the search conventions and their precedence, then pass the
+resulting `SearchConfig` source to the same `Load` or `LoadLayered` entry point.
+For example, the maintained sequence catalog puts a caller-selected file before
+a custom directory fallback while keeping its underlay and overlay choices
+independent. See [`sequence_catalog.go`](../../examples/consumers/sequence_catalog.go)
+and its [behavior tests](../../examples/consumers/sequence_catalog_test.go), plus
+the [working-directory executable example](../../examples/consumers/discovery_test.go).
+Together, the root-owned [discovery API](../../discovery.go) and [configuration
+discovery contract](../config.md#configuration-discovery) define ordered
+concatenation, directory-first Cartesian expansion, optional exhaustion, and
+selected-file behavior. [ADR 0019](../adr/0019-explicit-configuration-discovery.md)
+records why discovery is explicitly selected.
+
 ## Import defaults and selection inspection
 
 `Options.ImportDefaults` and `LayeredOptions.ImportDefaults` apply one