chore(deps): bump postcss from 8.4.19 to 8.4.31 in /docs (#474)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.19 to 8.4.31.
- [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/8.4.19...8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: indirect
...

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

docs/yarn.lock

@@ -7430,12 +7430,12 @@ __metadata:
   languageName: node
   linkType: hard
 
-"nanoid@npm:^3.3.4":
-  version: 3.3.4
-  resolution: "nanoid@npm:3.3.4"
+"nanoid@npm:^3.3.6":
+  version: 3.3.6
+  resolution: "nanoid@npm:3.3.6"
   bin:
     nanoid: bin/nanoid.cjs
-  checksum: 2fddd6dee994b7676f008d3ffa4ab16035a754f4bb586c61df5a22cf8c8c94017aadd360368f47d653829e0569a92b129979152ff97af23a558331e47e37cd9c
+  checksum: 7d0eda657002738aa5206107bd0580aead6c95c460ef1bdd0b1a87a9c7ae6277ac2e9b945306aaa5b32c6dcb7feaf462d0f552e7f8b5718abfc6ead5c94a71b3
   languageName: node
   linkType: hard
 
@@ -8414,13 +8414,13 @@ __metadata:
   linkType: hard
 
 "postcss@npm:^8.3.11, postcss@npm:^8.4.14, postcss@npm:^8.4.17, postcss@npm:^8.4.18":
-  version: 8.4.19
-  resolution: "postcss@npm:8.4.19"
+  version: 8.4.31
+  resolution: "postcss@npm:8.4.31"
   dependencies:
-    nanoid: ^3.3.4
+    nanoid: ^3.3.6
     picocolors: ^1.0.0
     source-map-js: ^1.0.2
-  checksum: 62782723a385f92b7525f66d29614624de7c5643855423db3a5efd9287e677650300192749adddbbb6734cea9b1d5f5fd4f6ea00ca3f9a95dbbb88f835f5ca64
+  checksum: 1d8611341b073143ad90486fcdfeab49edd243377b1f51834dc4f6d028e82ce5190e4f11bb2633276864503654fb7cab28e67abdc0fbf9d1f88cad4a0ff0beea
   languageName: node
   linkType: hard