chore(scripts): add update-stable-docs to release script (#5772)

Ref: https://github.com/prettier/prettier/pull/5676#issuecomment-449624247

scripts/release/steps/update-version.js

@@ -1,5 +1,6 @@
 "use strict";
 
+const execa = require("execa");
 const { logPromise, readJson, writeJson, processFile } = require("../utils");
 
 async function bump({ version }) {
@@ -14,6 +15,10 @@ async function bump({ version }) {
   processFile(".github/ISSUE_TEMPLATE/integration.md", content =>
     content.replace(/^(- Prettier Version: ).*?$/m, `$1${version}`)
   );
+
+  await execa("yarn", ["update-stable-docs"], {
+    cwd: "./website"
+  });
 }
 
 module.exports = async function(params) {

website/package.json

@@ -5,7 +5,8 @@
     "publish-gh-pages": "docusaurus-publish",
     "start": "concurrently \"docusaurus-start\" \"webpack -d -w\"",
     "svgo": "svgo --pretty --indent=2 --config=svgo.yml",
-    "svgo-all": "find static | grep '\\.svg$' | xargs -Iz -n 1 yarn svgo z"
+    "svgo-all": "find static | grep '\\.svg$' | xargs -Iz -n 1 yarn svgo z",
+    "update-stable-docs": "rm -rf ./versioned_docs ./versions.json && docusaurus-version stable"
   },
   "dependencies": {
     "clipboard": "2.0.0",