Make all examples executable

Author: asvetlov

examples/basic_srv.py

@@ -1,4 +1,6 @@
+#!/usr/bin/env python3
 """Basic http server with minimal setup"""
+
 import aiohttp
 import aiohttp.server
 

examples/web_srv.py

@@ -1,3 +1,7 @@
+#!/usr/bin/env python3
+"""Example for aiohttp.web basic server
+"""
+
 import asyncio
 import textwrap
 from aiohttp.web import Application, Response, StreamResponse