update changelog

CHANGELOG.md

@@ -12,7 +12,8 @@
   - <First `apollo-codegen-scala` related entry goes here>
 - `apollo-codegen-swift`
   - Added `CaseIterable` conformance so all known cases can be easily iterated.
-  - Switched to using mutli-line string literals when there's a multi-line string (mostly affects operation/fragment definitions)
+  - Added comment to `operationDefinition` to show the original query
+  - Stripped excess whitespace out of `operationDefinition`
   - Removed force-unwrap when the thing being unwrapped is a double optional
 - `apollo-codegen-typescript`
   - <First `apollo-codegen-typescript` related entry goes here>