Bump css-what from 3.3.0 to 5.0.1 in /docs

Bumps [css-what](https://github.com/fb55/css-what) from 3.3.0 to 5.0.1.
- [Release notes](https://github.com/fb55/css-what/releases)
- [Commits](https://github.com/fb55/css-what/compare/v3.3.0...v5.0.1)

---
updated-dependencies:
- dependency-name: css-what
  dependency-type: direct:production
...

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

docs/package.json

@@ -143,7 +143,7 @@
     "css-select-base-adapter": "^0.1.1",
     "css-tree": "^1.0.0-alpha.39",
     "css-unit-converter": "^1.1.2",
-    "css-what": "^3.3.0",
+    "css-what": "^5.0.1",
     "cssesc": "^3.0.0",
     "cssnano": "^4.1.10",
     "cssnano-preset-default": "^4.0.7",