feat: an example of intergration between externally created Application and dispatcher (#433)

* feat: an example of intergration between externally created Application and dispatcher

* fix: imports

* chore: fix EOF

* chore: fix comment

examples/separate_api_route_example.py

@@ -0,0 +1,34 @@
+# NOTE: This is an example of an integration between 
+# externally created Application object and the aiogram's dispatcher
+# This can be used for a custom route, for instance
+
+from aiogram import Bot, Dispatcher, types
+from aiogram.dispatcher.webhook import configure_app
+from aiohttp import web
+
+
+bot = Bot(token=config.bot_token)
+dp = Dispatcher(bot)
+
+
+
+@dp.message_handler(commands=["start"])
+async def cmd_start(message: types.Message):
+    await message.reply("start!")
+
+
+# handle /api route
+async def api_handler(request):
+    return web.json_response({"status": "OK"}, status=200)
+
+
+app = web.Application()
+# add a custom route
+app.add_routes([web.post('/api', api_handler)])
+# every request to /bot route will be retransmitted to dispatcher to be handled
+# as a bot update
+configure_app(dp, app, "/bot")
+
+
+if __name__ == '__main__':
+    web.run_app(app, port=9000)