feat: add example schema to start dev

CONTRIBUTING.md

@@ -52,7 +52,7 @@ npm run build
 To execute the application run:
 
 ```bash
-npm start -- -i input/file.yaml
+npm start -- -i example.yaml
 ```
 
 ### Clean

example.yaml

@@ -0,0 +1,24 @@
+openapi: 3.1.0
+info:
+  title: Sample API
+  description: Optional multiline or single-line description in [CommonMark](http://commonmark.org/help/) or HTML.
+  version: 0.1.9
+servers:
+  - url: http://api.example.com/v1
+    description: Optional server description, e.g. Main (production) server
+  - url: http://staging-api.example.com
+    description: Optional server description, e.g. Internal staging server for testing
+paths:
+  /users:
+    get:
+      summary: Returns a list of users.
+      description: Optional extended description in CommonMark or HTML.
+      responses:
+        '200':    # status code
+          description: A JSON array of user names
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  type: string