build: switch to legacy decorators

Author: ahochsteger

docs/babel.config.js

@@ -1,6 +1,6 @@
 module.exports = {
   plugins: [
-    ["@babel/plugin-proposal-decorators", { decoratorsBeforeExport: true }],
+    ["@babel/plugin-proposal-decorators", { legacy: true }],
     '@babel/plugin-transform-class-properties'
   ],
   presets: [require.resolve('@docusaurus/core/lib/babel/preset')],