docs: Add clarifying comments for stateless streamable HTTP endpoints

Add inline comments explaining why GET and DELETE endpoints return 405 in stateless mode:
- GET: SSE notifications not supported without session management
- DELETE: Session termination not needed in stateless mode

Author: dhodun

README.md

@@ -347,6 +347,7 @@ app.post('/mcp', async (req: Request, res: Response) => {
   }
 });
 
+// SSE notifications not supported in stateless mode
 app.get('/mcp', async (req: Request, res: Response) => {
   console.log('Received GET MCP request');
   res.writeHead(405).end(JSON.stringify({
@@ -359,6 +360,7 @@ app.get('/mcp', async (req: Request, res: Response) => {
   }));
 });
 
+// Session termination not needed in stateless mode
 app.delete('/mcp', async (req: Request, res: Response) => {
   console.log('Received DELETE MCP request');
   res.writeHead(405).end(JSON.stringify({