docs: Document a bot-specific note about which email address to use.

Author: klardotsh

send-message/README.md

@@ -8,7 +8,7 @@ This action sends a message to [Zulip](https://zulip.com/).
 | ------------------ | --------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `api-key`          | Yes       | [API key](https://zulip.com/api/api-keys) used to interact with the Zulip API. You can get an API key through Zulip's web interface. You should store the API key [as a secret](https://docs.github.com/en/actions/security-guides/encrypted-secrets#creating-encrypted-secrets-for-a-repository). |
 | `content`          | Yes       | The content of the message, formatted using [Zulip Markdown](https://zulip.com/help/format-your-message-using-markdown). Maximum message size of 10000 bytes.                                                                                                                                      |
-| `email`            | Yes       | Email address of the user who owns the API key mentioned above.                                                                                                                                                                                                                                    |
+| `email`            | Yes       | Email address of the user who owns the API key mentioned above. If using a bot, this should be the bot's email address, not the owning user's!                                                                                                                                                     |
 | `organization-url` | Yes       | Zulip organization canonical URL.                                                                                                                                                                                                                                                                  |
 | `to`               | Yes       | For stream messages, either the name or integer ID of the stream. For private messages, either a list containing integer user IDs or a list containing string email addresses.                                                                                                                     |
 | `topic`            | No        | The topic of the message. Only required for stream messages (`type="stream"`), ignored otherwise. Maximum length of 60 characters.                                                                                                                                                                 |