docs: Fix nightly storage docs

[calldelegation]

Description

https://vercel.com/fuel-labs/docs-hub/5r9LvMoawPA5PmVPTqX4p4FFcP8Q?filter=errors

This PR https://github.com/FuelLabs/sway/pull/6051/files broke a page in the docs because of a mislabeled anchor tag

sway {{#include ../../../../examples/advanced_storage_variables/src/main.sw:storage_string_import}}

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.