set version to v0.2.0

Author: Phil Varner

README.md

@@ -2,7 +2,7 @@
 
 - **OpenAPI specification:** TBD
 - **Conformance Classes:**
-  - <https://api.stacspec.org/v1.0.0-rc.2/aggregation>
+  - <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
 - **Dependencies:**
   - [Core](https://github.com/radiantearth/stac-api-spec/tree/v1.0.0-rc.2/core)