Bump postcss from 7.0.32 to 8.2.10 in /docs

Bumps [postcss](https://github.com/postcss/postcss) from 7.0.32 to 8.2.10.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/7.0.32...8.2.10)

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

docs/package.json

@@ -500,7 +500,7 @@
     "pkg-up": "^3.1.0",
     "portfinder": "^1.0.28",
     "posix-character-classes": "^1.0.0",
-    "postcss": "^7.0.32",
+    "postcss": "^8.2.10",
     "postcss-calc": "^7.0.2",
     "postcss-colormin": "^4.0.3",
     "postcss-convert-values": "^4.0.1",