update headmatter

Author: philvarner

README.md

@@ -1,11 +1,14 @@
 # STAC API - Aggregation Extension
 
+- **Title:** Aggregation
 - **OpenAPI specification:** TBD
 - **Conformance Classes:**
   - <https://api.stacspec.org/v0.2.0/aggregation>
-- **Extension [Maturity Classification](https://github.com/radiantearth/stac-api-spec/tree/v1.0.0-rc.2/README.md#maturity-classification):** Proposal
+- **Scope:** STAC API - Core
+- **Extension [Maturity Classification](https://github.com/radiantearth/stac-api-spec/tree/main/README.md#maturity-classification):** Proposal
 - **Dependencies:**
   - [Core](https://github.com/radiantearth/stac-api-spec/tree/v1.0.0-rc.2/core)
+- **Owner**: @philvarner
 
 The purpose of the Aggregation Extension is to provide an endpoint similar to the Search endpoint (`/search`), but which will provide aggregated information on matching Items rather than the Items themselves. This is highly influenced by the Elasticsearch aggregation endpoint, but with a more regular structure for responses.