Revert "chore(deps): update dependency vitepress to ^0.22.0 (#927)" (#946)

This reverts commit ec01c91.

Author: kazupon

package.json

@@ -136,7 +136,7 @@
     "ts-jest": "^26.5.4",
     "typescript": "4.2.3",
     "typescript-eslint-language-service": "^5.0.0",
-    "vitepress": "^0.22.0",
+    "vitepress": "^0.18.0",
     "vue": "^3.2.4",
     "vue-i18n": "workspace:*",
     "yorkie": "^2.0.0"