Add changelog for 0.2.0 release

CHANGELOG.rst

@@ -2,6 +2,28 @@
 Change log
 ##########
 
+0.2.0 (2022-02-09)
+==================
+
+This is the initial production candidate.
+Another release will be forthcoming to clean up some remaining issues, but this version contains the core functionality and uses a proper backend.
+
+The database schema of this version is incompatible with 0.1.0.
+The database must be wiped and recreated during the upgrade.
+
+- Use ``lsst.image_cutout_backend`` as the backend instead of ``pipetask`` without conversion of coordinates to pixels.
+- Data IDs are now Butler UUIDs instead of colon-separated tuples.
+- Support POLYGON and CIRCLE stencils and stop supporting POS RANGE, matching the capabilities of the new backend.
+- Use a separate S3 bucket to store the output rather than a Butler collection.
+  Eliminate use of Butler in the frontend, in favor of using that S3 bucket directly.
+  This eliminated the ``CUTOUT_BUTLER_COLLECTION`` configuration setting and adds new ``CUTOUT_STORAGE_URL`` and ``CUTOUT_TMPDIR`` configuration settings.
+- Use a different method of generating signed S3 result URLs that works correctly with workload identity in a GKE cluster.
+  This adds a new ``CUTOUT_SERVICE_ACCOUNT`` configuration setting specifying the service account to use for URL signing.
+  The workload identity the service runs as must have the ``roles/iam.serviceAccountTokenCreator`` role so that it can create signed URLs.
+- Add new ``--reset`` flag to ``vo-cutouts init`` to wipe the existing database.
+- Stop using a FastAPI subapp.
+  This was causing problems for error handling, leading to exceptions thrown in the UWS handlers to turn into 500 errors with no logged exception and no error details.
+
 0.1.0 (2021-11-11)
 ==================