Update release notes for December release (#2732)

docs/release-notes/release-2023-12-05.md

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+---
+title: December 2023
+---
+
+# Release Notes December 2023 (2023-12-05)
+
+:::danger
+This release contains **breaking changes**
+:::
+
+## New Features
+
+### `@typespec/compiler` New Features
+
+- **New Language Feature** Added string template literal in typespec. Single and multi-line strings can be interpolated with `${` and `}`. Example `\\Doc for url ${url} is here: ${location}\\`
+- [Emitter Framework]: `emitTypeReference` function takes an optional reference context that can be used to patch the context for the target.
+- [Emitter Framework]: Added `absolute-path` as a known format for emitter options which will validate the value passed by the user resolve to an absolute path.
+- [Emitter Framework]: Allow scalar and enum declarations to provide a reference context.
+- [Emitter Framework]: Allow passing a custom context when calling `emitType`.
+- Linter rules can now supply a full url to documentation.
+- Upgrade formatter to `prettier` version 3.1.
+
+### `@typespec/http` New Features
+
+- Add diagnostic when a namespace exists with routes, but no namespace is marked with `@service`.
+
+### `@typespec/json-schema` New Features
+
+- Add support for simple literal default on model properties.
+- Add support for `StringTemplate` literals.
+
+### `@typespec/openapi3` New Features
+
+- Now emits all properties of unreferenced schemas.
+- Treat union variants as Discriminator.
+- Emitter will now emit all properties of unreferenced schemas.
+
+### `@typespec/playground` New features
+
+- Add a format button to the playground command bar.
+- Add a notification to the standalone playground when the playground has been saved.
+- Enable changing the theme.
+- Add resizable panes for the editor and output
+- Add ability to pass a custom footer and use `Footer` and `FooterItem` component to build your own.
+- Add `noopener noreferrer` to footer external link
+- Move errors and warnings to a dedicated expandable banner at the bottom of the playground.
+- **BREAKING CHANGE** Styles must be imported seperately with `import \"@typespec/playground/styles.css\";`
+- Allow standalone playground to show a loading fallback.
+- Upgrade swagger-ui component.
+
+### `@typespec/rest` New Features
+
+- Fix issue with `ResourceCreateModel` template collecting \"update\" properties instead of \"create\" properties.
+
+## Bug Fixes
+
+### `@typespec/compiler` Bug Fixes
+
+- [Formatter]: Fix: Preserve parentheses in `valueof` expressions inside a union or array (e.g. `(value of strring) | Model`).
+- Fix: Union variants are now assigned to the parent union.
+
+### `@typespec/json-schema` Bug Fixes
+
+- Fix: Enum with a value of `0` would have resulted in `type` of `string` and `number`.
+- Fix: Scalar constraints combine with base scalar constraints.
+- Fix `@maxValueExclusive` setting `minimumExclusive` instead of `maximumExclusive`
+
+### `@typespec/openapi3` Bug Fixes
+
+- Fix: Report diagnostic instead of throwing errors in the case of duplicate ids or unknown scalar.
+- FIX: Handle `bytes` as a multipart part type correctly and produce `type: string, format: binary`
+
+### `@typespec/playground` Bug Fixes
+
+- Configure the program viewer to respect the color theme",
+
+### `@typespec/versioning` Bug Fixes
+
+- Fix crash in versioning library`.
+
+## Breaking Changes
+
+- **New Language Feature** string interpolation to strings in TypeSpec. Strings that use the sequence `${` are now expected to start a reference to an interpolated value. Strings that contain `${` and are not meant for interpolation must now be escaped with a `\`, like this: `\${`.
+
+### Semantic Changes in OpenApi3 Output
+
+- Previously, unreferenced `Model` types (types not used in any operation) were emitted using `read` visibility, meaning that properties that had only `create` or `update` visibility would not be included in the corresponding schema in the `@typespec/openapi3` emitter. In this release, all properties of unreferenced Model types will appear in the output.
+- Previously, `bytes` types that appeared in a `multipart/form-data` request or response would be marked as a base64 encoded string. In this release, `multipart/form-data` `bytes` types appearing in parts with an `object` type will be treated as a base64-encoded string, while those in non-model parts will appear as raw binary data.