x/website: tutorial index has wrong links for govulncheck pages

[seedpower]

What is the URL of the page with the issue?

https://go.dev/doc/tutorial/

What is your user agent?

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36

Screenshot

What did you do?

Click links.

What did you expect to see?

Show the right web page.

What did you see instead?

404, page not found.
https://go.dev/doc/tutorial/doc/tutorial/govulncheck -> https://go.dev/doc/tutorial/govulncheck
https://go.dev/doc/tutorial/doc/tutorial/govulncheck-ide -> https://go.dev/doc/tutorial/govulncheck-ide

[seankhliao]

cc @golang/vulndb

[gopherbot]

Change https://go.dev/cl/514635 mentions this issue: _content/doc/tutorial: fix vulncheck tutorial links