Bump postcss from 8.4.45 to 8.4.47 in /doc (#3163)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.45 to 8.4.47.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.45...8.4.47)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

doc/package.json

@@ -1,7 +1,7 @@
 {
   "devDependencies": {
     "autoprefixer": "^10.4.0",
-    "postcss": "^8.4.45",
+    "postcss": "^8.4.47",
     "postcss-cli": "^11.0.0"
   }
 }