updated changelog to reflect all the big reorg changes

CHANGELOG.md

@@ -8,8 +8,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - The landing page returns the conformance classes in a property `conformsTo`, which mirrors `GET /conformances` from OGC APIs.
+- Fragments - reusable OpenAPI documents for sort, filter, fields and context, along with explanation of how they work.
+- `conformsTo` JSON object in the landing page, to communicate what functionality a server implements.
+- Conformance classes for all the major functionality and extensions, to be referenced in the `conformsTo`.
+- ItemCollection moved from [STAC Core](https://github.com/radiantearth/stac-spec/blob/v0.9.0/item-spec/itemcollection-spec.md) to this repo.
 
 ### Changed
+- Major re-organization of the content and directory structure to make better conformance classes.
+  - STAC API Core is the landing page (a STAC catalog and conformance information).
+  - Item Search is the `search` cross-collection item search resource.
+  - STAC API - Features is the OGC API - Features standards to be used in a STAC API.
+  - Extensions are specified in the relevant functionality directory, though they can share openapi yaml's in the 'fragments' directory.
 - Updated to STAC specification version 1.0.0-beta.2
 - Named explicit supported STAC core versions to be from 0.9.0 up to (and not including) 2.0.0
 - Context Extension OpenAPI spec was updated to remove the no longer used `next` attribute