docs: precede code snippet with standard sentence formatting (#1386)

Author: srtaalej

docs/english/concepts/message-sending.md

@@ -49,7 +49,7 @@ You can have your app's messages stream in to replicate conventional AI chatbot
 * [`chat_appendStream`](/reference/methods/chat.appendstream)
 * [`chat_stopStream`](/reference/methods/chat.stopstream)
 
-The Python Slack SDK provides a [`chat_stream()`](https://docs.slack.dev/tools/python-slack-sdk/reference/web/client.html#slack_sdk.web.client.WebClient.chat_stream) helper utility to streamline calling these methods. Here's an excerpt from our [Assistant template app](https://github.com/slack-samples/bolt-python-assistant-template)
+The Python Slack SDK provides a [`chat_stream()`](https://docs.slack.dev/tools/python-slack-sdk/reference/web/client.html#slack_sdk.web.client.WebClient.chat_stream) helper utility to streamline calling these methods. Here's an excerpt from our [Assistant template app](https://github.com/slack-samples/bolt-python-assistant-template):
 
 ```python
 streamer = client.chat_stream(