(doc): add example of open api generator

README.md

@@ -79,6 +79,61 @@ fun Application.minimalExample() {
 }
 ```
 
+## Ktor OpenAPI Generator & Swagger UI
+
+Ktor OpenAPI plugin (with support for Ktor `2.x.y`) that generates OpenAPI from your routes definition and allows you to
+host Swagger UI. Hosted on different
+repository: [LukasForst/ktor-openapi-generator](https://github.com/LukasForst/ktor-openapi-generator/) as it is a fork
+of popular [papsign/Ktor-OpenAPI-Generator](https://github.com/papsign/Ktor-OpenAPI-Generator) with some refactoring and
+support for Ktor `2.x.y`.
+
+It supports most of the stuff from Ktor including JWT and Session auth.
+
+```kotlin
+/**
+ * Minimal example of OpenAPI plugin for Ktor.
+ */
+fun Application.minimalExample() {
+    // install OpenAPI plugin
+    install(OpenAPIGen) {
+        // this automatically servers Swagger UI on /swagger-ui
+        serveSwaggerUi = true
+        info {
+            title = "Minimal Example API"
+        }
+    }
+    // install JSON support
+    install(ContentNegotiation) {
+        jackson()
+    }
+    // add basic routes for openapi.json and redirect to UI
+    routing {
+        // serve openapi.json
+        get("/openapi.json") {
+            call.respond(this@routing.application.openAPIGen.api.serialize())
+        }
+        // and do redirect to make it easier to remember
+        get("/swagger-ui") {
+            call.respondRedirect("/swagger-ui/index.html?url=/openapi.json", true)
+        }
+    }
+    // and now example routing
+    apiRouting {
+        route("/example/{name}") {
+            // SomeParams are parameters (query or path), SomeResponse is what the backend returns and SomeRequest
+            // is what was passed in the body of the request
+            post<SomeParams, SomeResponse, SomeRequest> { params, someRequest ->
+                respond(SomeResponse(bar = "Hello ${params.name}! From body: ${someRequest.foo}."))
+            }
+        }
+    }
+}
+
+data class SomeParams(@PathParam("who to say hello") val name: String)
+data class SomeRequest(val foo: String)
+data class SomeResponse(val bar: String)
+```
+
 ## Ktor Rate Limiting
 
 A simple library that enables Rate Limiting in Ktor.