Added Openapi spec/swagger UI - added swagger to python requirements.txt

docs/api.md

@@ -0,0 +1,31 @@
+# API Reference
+
+This page contains the interactive API documentation for ntfy. You can try out the API endpoints directly from this page.
+
+## Using the API Documentation
+
+### Server Selection
+
+The Swagger UI includes a server selector dropdown at the top of the page. By default, it's configured to use the **public ntfy.sh server**.
+
+To use your own ntfy instance, edit `docs/swagger_api/openapi.yaml` and add your server URL to the `servers` section:
+
+```yaml
+servers:
+  - url: https://ntfy.sh
+    description: Public ntfy server
+  - url: https://your-ntfy-instance.com
+    description: Your custom server
+```
+
+After editing the file, rebuild the docs with `mkdocs build`.
+
+### Authentication
+
+Click the **Authorize** button (lock icon) in Swagger UI to add your access token. Use the format `Bearer <your_token>` or `Basic <base64_encoded_credentials>`.
+
+### Try It Out
+
+Click **Try it out** on any endpoint to test it directly. Parameters will be empty by default - enter your own values to test.
+
+<swagger-ui src="swagger_api/openapi.yaml"/>