Describe Gitea's purpose more accurately (go-gitea#23698)

As title.

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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Yarden Shoham <git@yardenshoham.com>

Author: 3 people

docs/content/page/index.en-us.md

@@ -10,8 +10,8 @@ draft: false
 
 # What is Gitea?
 
-Gitea is a painless self-hosted Git service. It is similar to GitHub, Bitbucket, and GitLab.
-Gitea is a fork of [Gogs](http://gogs.io). See the [Gitea Announcement](https://blog.gitea.io/2016/12/welcome-to-gitea/)
+Gitea is a painless self-hosted all-in-one software development service, it includes Git hosting, code review, team collaboration, package registry and CI/CD. It is similar to GitHub, Bitbucket and GitLab.
+Gitea was forked from [Gogs](http://gogs.io) originally and almost all the code has been changed. See the [Gitea Announcement](https://blog.gitea.io/2016/12/welcome-to-gitea/)
 blog post to read about the justification for a fork.
 
 ## Purpose