doc: fix incorrect example of @statusCode (#3230)

## Issue Description
There is a example of `TypeSpec.http.@statusCode`
[here](https://typespec.io/docs/next/libraries/http/reference/decorators#@TypeSpec.Http.statusCode).
However, the property name is missing in this example. Due to this, the
code did not work as expected.

```
op read(): {@statuscode: 200, @Body pet: Pet}
op create(): {@statuscode: 201 | 202}
```

Instead, specifying the property name as follows made it work correctly:

```
op read(): {
  @statuscode _: 200;
  @Body pet: Widget;
};
op create(): {
  @statuscode _: 201 | 202;
};
```

## Fix Description
- Corrected examples of `TypeSpec.http.@statusCode` in the reference and
documentation.

---------

Co-authored-by: Timothee Guerin <tiguerin@microsoft.com>
Co-authored-by: Timothee Guerin <timothee.guerin@outlook.com>
Co-authored-by: Mark Cowlishaw <markcowl@microsoft.com>

.chronus/changes/fix-example-of-statusCode-2024-5-3-20-58-17.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: internal
+packages:
+  - "@typespec/http"
+---
+
+doc: fix incorrect example of `@statusCode`

docs/libraries/http/reference/decorators.md

@@ -462,8 +462,13 @@ None
 #### Examples
 
 ```typespec
-op read(): {@statusCode: 200, @body pet: Pet}
-op create(): {@statusCode: 201 | 202}
+op read(): {
+  @statusCode _: 200;
+  @body pet: Pet;
+};
+op create(): {
+  @statusCode _: 201 | 202;
+};
 ```
 
 ### `@useAuth` {#@TypeSpec.Http.useAuth}

packages/http/README.md

@@ -509,8 +509,13 @@ None
 ##### Examples
 
 ```typespec
-op read(): {@statusCode: 200, @body pet: Pet}
-op create(): {@statusCode: 201 | 202}
+op read(): {
+  @statusCode _: 200;
+  @body pet: Pet;
+};
+op create(): {
+  @statusCode _: 201 | 202;
+};
 ```
 
 #### `@useAuth`

packages/http/generated-defs/TypeSpec.Http.ts

@@ -12,8 +12,13 @@ import type {
  *
  * @example
  * ```typespec
- * op read(): {@statusCode: 200, @body pet: Pet}
- * op create(): {@statusCode: 201 | 202}
+ * op read(): {
+ *   @statusCode _: 200;
+ *   @body pet: Pet;
+ * };
+ * op create(): {
+ *   @statusCode _: 201 | 202;
+ * };
  * ```
  */
 export type StatusCodeDecorator = (context: DecoratorContext, target: ModelProperty) => void;

packages/http/lib/http-decorators.tsp

@@ -128,8 +128,13 @@ extern dec bodyIgnore(target: ModelProperty);
  * @example
  *
  * ```typespec
- * op read(): {@statusCode: 200, @body pet: Pet}
- * op create(): {@statusCode: 201 | 202}
+ * op read(): {
+ *   @statusCode _: 200;
+ *   @body pet: Pet;
+ * };
+ * op create(): {
+ *   @statusCode _: 201 | 202;
+ * };
  * ```
  */
 extern dec statusCode(target: ModelProperty);