Upgrade docs postcss (#13031)

docs/package-lock.json

@@ -10693,9 +10693,9 @@
       }
     },
     "node_modules/postcss": {
-      "version": "8.4.26",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.26.tgz",
-      "integrity": "sha512-jrXHFF8iTloAenySjM/ob3gSj7pCu0Ji49hnjqzsgSRa50hkWCKD0HQ+gMNJkW38jBI68MpAAg7ZWwHwX8NMMw==",
+      "version": "8.4.31",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.31.tgz",
+      "integrity": "sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==",
       "funding": [
         {
           "type": "opencollective",