Add changelog entry for AWS Lambda.

CHANGES.md

@@ -1,13 +1,12 @@
-Unreleased
+1.2.1
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+
 - Add KMS support (#118 @zbaylin)
 - Drop dependency on ocaml-migrate-parsetree and use ocaml-compiler-libs (#126 @Nymphium)
-
-1.2.1
-----------
-- Increase lower bound on OCaml to 4.08. https://github.com/inhabitedtype/ocaml-aws/pull/104
-- Migrate CI to github actions https://github.com/inhabitedtype/ocaml-aws/pull/104
-- Add STS `assume_role` token support https://github.com/inhabitedtype/ocaml-aws/pull/117
+- Increase lower bound on OCaml to 4.08. (#104 @tmcgilchrist)
+- Migrate CI to github actions (#104 @tmcgilchrist)
+- Add STS `assume_role` token support (#117 @zbaylin @UnrealAkama @bleepbloopsify)
+- Initial AWS Lambda support (#108 @tmcgilchrist)
 
 1.2: (24-01-2020)
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