docs: duplicate error, fail sections

[hyunbinseo]

Describe the bug

For some reason, there are duplicate error and fail documentations.

Reproduction

• https://kit.svelte.dev/docs/modules#sveltejs-kit-error
• https://kit.svelte.dev/docs/modules#sveltejs-kit-fail

Logs

No response

System Info

Not applicable

Severity

annoyance

Additional Information

No response

[dummdidumm]

Closing as duplicate of #7853