Add a changelog (#33)

Author: ggrossetie

CHANGELOG.md

@@ -0,0 +1,60 @@
+# Zulip GitHub Action Changelog
+
+## Unreleased
+
+**Breaking changes**
+
+⚠️ Please use `zulip/github-actions-zulip/send-message@v1` instead of `yuzutech/zulip-send-message-action@v0.1.2`.  
+If you were using `password` as authentification method, please get an API key through Zulip's web interface and use `api-key` instead.
+Finally, `username` field was renamed to `email` to be consistent with Zulip API naming.
+
+_Before_
+
+```yml
+- name: Send a stream message
+  uses: yuzutech/zulip-send-message-action@v0.1.0
+  with:
+    username: 'username@example.com'
+    api-key: 'abcd1234'
+    organization-url: 'https://org.zulipchat.com'
+    to: 'social'
+    type: 'stream'
+    topic: 'Castle'
+    content: 'I come not, friends, to steal away your hearts.'
+```
+
+_After_
+
+```yml
+- name: Send a stream message
+  uses: zulip/github-actions-zulip/send-message@v1
+  with:
+    email: 'username@example.com'
+    api-key: 'abcd1234'
+    organization-url: 'https://org.zulipchat.com'
+    to: 'social'
+    type: 'stream'
+    topic: 'Castle'
+    content: 'I come not, friends, to steal away your hearts.'
+```
+
+- Align naming with Zulip API
+   * Remove `password` as this authentification method is not recommended (the preferred auth method is via `api-key`)
+   * Rename `username` to `email` for consistency
+- Transfer the repository to the `@zulip` organization
+- Move the "send message action" to a subdirectory
+
+**Improvements**
+
+- Catch unexpected errors to provide better error messages
+
+**Infrastructure**
+
+- Bump `@actions/core` from 1.2.6 to 1.4.0
+- Bump `@actions/github` from 4.0.0 to 5.0.0
+- Bump `eslint` from 7.21.0 to 7.30.0
+- Use a bot account for integration tests
+
+**Documentation**
+
+- Mention that you can format messages using [Zulip Markdown](https://zulip.com/help/format-your-message-using-markdown)