docs: fixes heading issues

Signed-off-by: Vincent Biret <[email protected]>

Author: baywet

docs/upgrade-guide-2.md

@@ -413,7 +413,7 @@ public class OpenApiComponents : IOpenApiSerializable, IOpenApiExtensible
 }
 ```
 
-#### Summary and Description alongside $ref
+### Summary and Description alongside $ref
 
 Through the use of proxy objects in order to represent references, it is now possible to set the Summary and Description property on an object that is a reference. This was previously not possible.
 
@@ -424,6 +424,13 @@ var parameter = new OpenApiParameterReference("id", hostdocument)
 };
 ```
 
+Once serialized results in:
+
+```yaml
+$ref: id
+description: Customer Id
+```
+
 ### Use HTTP Method Object Instead of Enum
 
 HTTP methods are now represented as objects instead of enums. This change enhances flexibility but requires updates to how HTTP methods are handled in your code.
@@ -443,7 +450,7 @@ OpenApiOperation operation = new OpenApiOperation
 };
 ```
 
-#### 3. References as Components
+### References as Components
 
 References can now be used as components, allowing for more modular and reusable OpenAPI documents.
 
@@ -465,9 +472,9 @@ OpenApiComponents components = new OpenApiComponents
 {
     Schemas = new Dictionary<string, IOpenApiSchema>
     {
-        ["MySchema"] = new OpenApiSchema
+        ["MySchema"] = new OpenApiSchemaReference("MyOtherSchema")
         {
-            Reference = new OpenApiSchemaReference("MySchema")
+            Description = "Other reusable schema from initial schema"
         }
     }
 };