Added JSON schema

Author: squidfunk

.vscode/settings.json

@@ -7,5 +7,12 @@
   },
   "search.followSymlinks": false,
   "stylelint.validate": ["css", "scss"],
-  "typescript.tsdk": "node_modules/typescript/lib"
+  "typescript.tsdk": "node_modules/typescript/lib",
+  "yaml.schemas": {
+    "docs/schema.json": "mkdocs.yml"
+  },
+  "yaml.customTags": [
+    "!ENV scalar",
+    "!ENV sequence"
+  ]
 }