created the validation service and swagger set up

src/config/env.validation.ts

@@ -17,4 +17,4 @@ export const envValidationSchema = Joi.object({
   REDIS_PORT: Joi.number().required(),
 
   JWT_SECRET: Joi.string().min(10).required(),
-});
+});

src/config/swagger.config.ts

@@ -0,0 +1,39 @@
+import { INestApplication } from '@nestjs/common';
+import { SwaggerModule, DocumentBuilder } from '@nestjs/swagger';
+
+export function setupSwagger(app: INestApplication): void {
+  const config = new DocumentBuilder()
+    .setTitle('TeachLink API')
+    .setDescription('TeachLink backend API documentation')
+    .setVersion('1.0')
+    .addBearerAuth(
+      {
+        type: 'http',
+        scheme: 'bearer',
+        bearerFormat: 'JWT',
+        name: 'Authorization',
+        description: 'Enter JWT token',
+        in: 'header',
+      },
+      'access-token',
+    )
+    .addTag('Auth', 'Authentication and authorization endpoints')
+    .addTag('Users', 'User management endpoints')
+    .addTag('Courses', 'Course management endpoints')
+    .addTag('Payments', 'Payment processing endpoints')
+    .addTag('Subscriptions', 'Subscription management endpoints')
+    .addServer('http://localhost:3000', 'Local Development')
+    .addServer('https://api.teachlink.com', 'Production')
+    .build();
+
+  const document = SwaggerModule.createDocument(app, config);
+
+  SwaggerModule.setup('api/docs', app, document, {
+    swaggerOptions: {
+      persistAuthorization: true,
+      tagsSorter: 'alpha',
+      operationsSorter: 'alpha',
+    },
+    customSiteTitle: 'TeachLink API Docs',
+  });
+}