Bump node-sass from 4.13.1 to 7.0.0 in /docs

Bumps [node-sass](https://github.com/sass/node-sass) from 4.13.1 to 7.0.0.
- [Release notes](https://github.com/sass/node-sass/releases)
- [Changelog](https://github.com/sass/node-sass/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sass/node-sass/compare/v4.13.1...v7.0.0)

---
updated-dependencies:
- dependency-name: node-sass
  dependency-type: direct:development
...

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

docs/package.json

@@ -12,7 +12,7 @@
     "gulp": "^4.0.2",
     "gulp-run": "^1.7.1",
     "gulp-sass": "^4.0.1",
-    "node-sass": "^4.13.1"
+    "node-sass": "^7.0.0"
   },
   "dependencies": {}
 }