Refactor and improve bot examples (#1256)

* Refactor and improve bot messages

Refactored bot code to use aiogram enumerations and enhanced chat messages with markdown beautifications for a more user-friendly display.

CommandStart() is now used instead of Command('start') for readability.

Furthermore, the bot's 'stop' command was improved, ensuring it executes appropriately during KeyboardInterrupt or SystemExit.

Additionally, the bot's logging was adjusted to output to sys.stdout for better logs' readability.

* Added Changelog

* Add guidance comments on obtaining bot tokens from environment variables

* Remove hardcoded tokens, opt for environment variable

* Remove unnecessary spaces and reorganize imports

* Fix error, switch default storage from Redis to Memory, and add logging to multibot example

examples/echo_bot.py

@@ -1,19 +1,22 @@
 import asyncio
 import logging
+import sys
+from os import getenv
 
 from aiogram import Bot, Dispatcher, Router, types
 from aiogram.enums import ParseMode
-from aiogram.filters import Command
+from aiogram.filters import CommandStart
 from aiogram.types import Message
+from aiogram.utils.markdown import hbold
 
 # Bot token can be obtained via https://t.me/BotFather
-TOKEN = "42:TOKEN"
+TOKEN = getenv("BOT_TOKEN")
 
 # All handlers should be attached to the Router (or Dispatcher)
 router = Router()
 
 
-@router.message(Command("start"))
+@router.message(CommandStart())
 async def command_start_handler(message: Message) -> None:
     """
     This handler receives messages with `/start` command
@@ -23,7 +26,7 @@ async def command_start_handler(message: Message) -> None:
     # and the target chat will be passed to :ref:`aiogram.methods.send_message.SendMessage`
     # method automatically or call API method directly via
     # Bot instance: `bot.send_message(chat_id=message.chat.id, ...)`
-    await message.answer(f"Hello, <b>{message.from_user.full_name}!</b>")
+    await message.answer(f"Hello, {hbold(message.from_user.full_name)}!")
 
 
 @router.message()
@@ -54,5 +57,8 @@ async def main() -> None:
 
 
 if __name__ == "__main__":
-    logging.basicConfig(level=logging.INFO)
-    asyncio.run(main())
+    logging.basicConfig(level=logging.INFO, stream=sys.stdout)
+    try:
+        asyncio.run(main())
+    except (KeyboardInterrupt, SystemExit):
+        logging.info("Bot stopped!")