Bump postcss from 8.4.14 to 8.4.31 in /docs

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.14 to 8.4.31.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.14...8.4.31)

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

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

Author: dependabot[bot]

docs/yarn.lock

@@ -6311,10 +6311,10 @@ multicast-dns@^7.2.5:
     dns-packet "^5.2.2"
     thunky "^1.0.2"
 
-nanoid@^3.3.4:
-  version "3.3.4"
-  resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.3.4.tgz#730b67e3cd09e2deacf03c027c81c9d9dbc5e8ab"
-  integrity sha512-MqBkQh/OHTS2egovRtLk45wEyNXwF+cokD+1YPf9u5VfJiRdAiRwB2froX5Co9Rh20xs4siNPm8naNotSD6RBw==
+nanoid@^3.3.6:
+  version "3.3.6"
+  resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.3.6.tgz#443380c856d6e9f9824267d960b4236ad583ea4c"
+  integrity sha512-BGcqMMJuToF7i1rt+2PWSNVnWIkGCU78jBG3RxO/bZlnZPK2Cmi2QaffxGO/2RvWi9sL+FAiRiXMgsyxQ1DIDA==
 
 negotiator@0.6.3:
   version "0.6.3"
@@ -7043,11 +7043,11 @@ postcss-zindex@^5.1.0:
   integrity sha512-fgFMf0OtVSBR1va1JNHYgMxYk73yhn/qb4uQDq1DLGYolz8gHCyr/sesEuGUaYs58E3ZJRcpoGuPVoB7Meiq9A==
 
 postcss@^8.3.11, postcss@^8.4.13, postcss@^8.4.14, postcss@^8.4.7:
-  version "8.4.14"
-  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.14.tgz#ee9274d5622b4858c1007a74d76e42e56fd21caf"
-  integrity sha512-E398TUmfAYFPBSdzgeieK2Y1+1cpdxJx8yXbK/m57nRhKSmk1GB2tO4lbLBtlkfPQTDKfe4Xqv1ASWPpayPEig==
+  version "8.4.31"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.31.tgz#92b451050a9f914da6755af352bdc0192508656d"
+  integrity sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==
   dependencies:
-    nanoid "^3.3.4"
+    nanoid "^3.3.6"
     picocolors "^1.0.0"
     source-map-js "^1.0.2"