JudgeServer API doc page lost

[alexwenbj]

Describe the bug The link to JudgeServer API doc page lost. To Reproduce Steps to reproduce the behavior:

1. Go to '...'
2. Show 404 page

Expected behavior Should show the help page.

Screenshots If applicable, add screenshots to help explain your problem.

System (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Additional context Add any other context about the problem here.