Add release notes release 0.55 - April 2024 (#3093)

Co-authored-by: Mark Cowlishaw <markcowl@microsoft.com>

.chronus/changes/fix-no-crash-nullable-2024-1-28-22-57-44.md

@@ -5,4 +5,4 @@ packages:
   - "@typespec/openapi3"
 ---
 
-Fix crash: emit `{nulable: true}` when trying to emit `null` in openapi3
+Fix crash: emit `{nullable: true}` when trying to emit `null` in openapi3

docs/release-notes/release-2024-04-02.md

@@ -0,0 +1,65 @@
+---
+title: 0.55 - April 2024
+---
+
+# Release Notes Version 0.55 - April 2024
+
+:::warning
+This release contains deprecations
+:::
+
+## Deprecations
+
+### @typespec/compiler
+
+- [#2910](https://github.com/microsoft/typespec/pull/2910) Deprecate `@projectedName` decorator. `@encodedName` should be used instead.
+
+  Example:
+
+  ```diff
+  -@projectedName("json", "exp")
+  +@encodedName("application/json", "exp")
+  ```
+
+- [#3094](https://github.com/microsoft/typespec/pull/3094) Deprecate `@knownValues` decorator. Use a named union of string literal with a string variant to achieve the same result without a decorator
+
+  Example:
+
+  ```diff
+  -enum FooKV { a, b, c}
+  -@knownValues(FooKV)
+  -scalar foo extends string;
+  +union Foo { "a", "b", "c", string }
+  ```
+
+## Features
+
+### @typespec/compiler
+
+- [#2992](https://github.com/microsoft/typespec/pull/2992) Enable the use of `@encode` for model properties that have a union type. This supports cases like `@encode("rfc3339") prop: utcDateTime | null`
+
+### @typespec/versioning
+
+- [#3053](https://github.com/microsoft/typespec/pull/3053) Add support for versioning of scalars(Added, removed, renamed)
+
+## Bug Fixes
+
+### @typespec/compiler
+
+- [#3018](https://github.com/microsoft/typespec/pull/3018) Grammar: Fix comments in template params not tokenized
+- [#3052](https://github.com/microsoft/typespec/pull/3052) Fix: Union template declaration were incorrectly being finished in projection
+- [#2983](https://github.com/microsoft/typespec/pull/2983) Warnings converted to error with `warn-as-error` do not prevent compilation from moving to the next stage like regular warnings
+- [#3041](https://github.com/microsoft/typespec/pull/3041) Improve reliability of application of codefixes in IDE, often it would not do anything
+- [#3069](https://github.com/microsoft/typespec/pull/3069) TmLanguage: Fix tokenization of escaped identifiers, enums and unions
+
+### @typespec/openapi3
+
+- [#3077](https://github.com/microsoft/typespec/pull/3077) Do not crash if using an unsupported intrinsic type
+- [#2967](https://github.com/microsoft/typespec/pull/2967) Fix crash: emit `{nullable: true}` when trying to emit `null` in openapi3
+- [#3013](https://github.com/microsoft/typespec/pull/3013) Fix: OpenAPI3 not marking part of bytes or something else as `format: binary`
+- [#3090](https://github.com/microsoft/typespec/pull/3090) Fix: Literal unions with the same variants keep adding duplicate entries
+- [#3049](https://github.com/microsoft/typespec/pull/3049) Fix visibility naming conflict when a model used with `extends` was used in different visibility.
+
+### @typespec/eslint-config-typespec
+
+- [#2122](https://github.com/microsoft/typespec/pull/2122) Ignore `generated-defs` folder