[Bug] Discord link is invalid

[euoia]

Initial checklist

• I agree to follow the code of conduct
• I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Affected packages and versions

README

Link to runnable example

No response

Steps to reproduce

1. Open the GitHub repo https://github.com/Milkdown/milkdown
2. Click on Welcome to join our Discord community.

Expected behavior

Open the Discord server.

Actual behavior

Link is invalid.

Runtime

No response

OS

No response

Build and bundle tools

No response