Update docusaurus monorepo to v2.0.0-beta.15

Author: renovate-bot

package.json

@@ -14,8 +14,8 @@
     "write-heading-ids": "docusaurus write-heading-ids"
   },
   "dependencies": {
-    "@docusaurus/core": "2.0.0-beta.14",
-    "@docusaurus/preset-classic": "2.0.0-beta.14",
+    "@docusaurus/core": "2.0.0-beta.15",
+    "@docusaurus/preset-classic": "2.0.0-beta.15",
     "@easyops-cn/docusaurus-search-local": "0.21.4",
     "@mdx-js/react": "1.6.22",
     "@svgr/webpack": "6.1.2",