updated to docusaurus beta 15

Author: Tigerpanzer02

package.json

@@ -12,8 +12,8 @@
     "clear": "docusaurus clear"
   },
   "dependencies": {
-    "@docusaurus/core": "^2.0.0-beta.13",
-    "@docusaurus/preset-classic": "^2.0.0-beta.13",
+    "@docusaurus/core": "^2.0.0-beta.15",
+    "@docusaurus/preset-classic": "^2.0.0-beta.15",
     "@mdx-js/react": "^1.6.21",
     "clsx": "^1.1.1",
     "react": "^16.8.4",