add a sample swift config

lib/mix/tasks/sample_config.eex

@@ -44,3 +44,21 @@ config :pleroma, Pleroma.Repo,
 # For using third-party S3 clones like wasabi, also do:
 # config :ex_aws, :s3,
 #   host: "s3.wasabisys.com"
+
+
+# Configure Openstack Swift support if desired.
+# 
+# Many openstack deployments are different, so config is left very open with 
+# no assumptions made on which provider you're using. This should allow very 
+# wide support without needing separate handlers for OVH, Rackspace, etc.
+#
+# config :pleroma, Pleroma.Uploaders.Swift,
+#  container: "some-container",
+#  username: "api-username-yyyy",
+#  password: "api-key-xxxx",
+#  tenant_id: "<openstack-project/tenant-id>",
+#  auth_url: "https://keystone-endpoint.provider.com",
+#  storage_url: "https://swift-endpoint.prodider.com/v1/AUTH_<tenant>/<container>",
+#  object_url: "https://cdn-endpoint.provider.com/<container>"
+#
+