build(deps-dev): bump eslint-config-next from 15.1.7 to 15.5.6 in /docs

Bumps [eslint-config-next](https://github.com/vercel/next.js/tree/HEAD/packages/eslint-config-next) from 15.1.7 to 15.5.6.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](https://github.com/vercel/next.js/commits/v15.5.6/packages/eslint-config-next)

---
updated-dependencies:
- dependency-name: eslint-config-next
  dependency-version: 15.5.6
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/package-lock.json

@@ -22,7 +22,7 @@
     "@typescript-eslint/parser": "^8.25.0",
     "autoprefixer": "^10.4.16",
     "eslint": "^8",
-    "eslint-config-next": "^15.1.7",
+    "eslint-config-next": "^15.5.6",
     "eslint-config-prettier": "^10.0.1",
     "eslint-plugin-jest": "^28.11.0",
     "eslint-plugin-prettier": "^5.1.2",