Update ROADMAP.md

ROADMAP.md

@@ -9,7 +9,7 @@ We use the [Projects](https://github.com/orgs/yorkie-team/projects) feature in G
 
 ## Yorkie v0.1
 
-Yorkie's first release version, v0.1, aims to implement the basic features of the document store for building collaborative editing applications. And it should be reliably available for services used in production environments.
+Yorkie's first release version, v0.1, aims to implement the basic features of the document store for building collaborative editing applications.
 
 ### 2019
  - Nov: Start the project with adding basic structure(Agent, Client, Document)
@@ -25,11 +25,13 @@ Yorkie's first release version, v0.1, aims to implement the basic features of th
  - Aug:
    - Peer Awareness [#48](https://github.com/yorkie-team/yorkie/issues/48)
    - Introducing Prometheus metrics [#76](https://github.com/yorkie-team/yorkie/issues/76)
- - Sep: Supporting TLS and Auth webhook to secure Yorkie [#6](https://github.com/yorkie-team/yorkie/issues/6)
- - Nov: Introducing HA [#11](https://github.com/yorkie-team/yorkie/issues/11)
- - Dec: Redo/Undo API [#49](https://github.com/yorkie-team/yorkie/issues/49)
+ - Dec: Cleanup such as package dependency cleanup and tests cleanup
 
 ## Yorkie v0.2
 
+Yorkie v0.2 should be reliably available for services used in production environments.
+
 ### 2021
- - Jan: Speed up push/pull changes and snapshot
+ - Jan: Introducing HA [#11](https://github.com/yorkie-team/yorkie/issues/11)
+ - Feb: Supporting TLS and Auth webhook to secure Yorkie [#6](https://github.com/yorkie-team/yorkie/issues/6)
+ - Apr: Redo/Undo API [#49](https://github.com/yorkie-team/yorkie/issues/49)