docs: Add README docs for event-handler package

Author: karthikeyanjp

packages/event-handler/README.md

@@ -0,0 +1,85 @@
+# digital-event-handler
+
+Minimalistic event handler & HTTP router for Serverless applications
+
+## Simple Example
+
+```typescript
+// Import API Gateway Event handler
+import { APIGatewayProxyEvent, Context } from 'aws-lambda';
+import { ApiGatewayResolver } from './ApiGateway';
+import { AsyncFunction, BaseProxyEvent, JSONData } from 'types';
+
+// Initialize the event handler
+const app = new ApiGatewayResolver();
+
+// Define a route
+const helloHandler = 
+async (_event: BaseProxyEvent, _context: Context) : Promise<JSONData> => Promise.resolve({ message: 'Hello World' });
+
+// Register Route
+app.addRoute('GET', '/v1/hello', helloHandler as AsyncFunction) ;
+
+// Declare your Lambda handler
+// Declare your Lambda handler
+exports.handler = (
+  _event: APIGatewayProxyEvent,
+  _context: Context
+): Promise<JSONData> => 
+  // Resolve routes
+  app.resolve(_event, _context)
+;
+```
+
+## Register Route with Decorators
+
+```typescript
+import { APIGatewayProxyEvent, Context } from 'aws-lambda';
+import { ApiGatewayResolver } from './ApiGateway';
+import { BaseProxyEvent, JSONData } from 'types';
+
+// Initialize the event handler
+const app = new ApiGatewayResolver();
+
+// Define a Controller class
+export class HelloController{
+
+  // Register a route
+  @app.get('/v1/hello')
+  public hello (_event: BaseProxyEvent, _context: Context) : Promise<JSONData> {
+    return Promise.resolve({ message: 'Hello World' });
+  }
+  
+  @app.post('/v1/hello')
+  public postHello (_event: BaseProxyEvent, _context: Context) : Promise<JSONData> {
+    return Promise.resolve({ message: 'Resource created' });
+  }
+  
+}
+
+// Declare your Lambda handler
+exports.handler = (
+  _event: APIGatewayProxyEvent,
+  _context: Context
+): Promise<JSONData> => 
+  // Resolve routes
+  app.resolve(_event, _context)
+;
+
+```
+
+## CORS Support
+
+```typescript
+// Import API Gateway Event handler
+import { CORSConfig } from 'types';
+import { ApiGatewayResolver, ProxyEventType } from './ApiGateway';
+
+// App with CORS Configurattion
+const app = new ApiGatewayResolver(
+  ProxyEventType.APIGatewayProxyEvent,
+  new CORSConfig()
+);
+
+```
+