Update nextra monorepo to v2

Author: renovate[bot]

package.json

@@ -12,8 +12,8 @@
     "license": "MIT",
     "dependencies": {
         "next": "^12.0.0",
-        "nextra": "^1.1.0",
-        "nextra-theme-docs": "^1.2.2",
+        "nextra": "^2.0.0",
+        "nextra-theme-docs": "^2.0.0",
         "react": "^17.0.1",
         "react-dom": "^17.0.1",
         "sharp": "^0.29.1"