Remove useless dev deps

Author: MoOx

package.json

@@ -85,9 +85,6 @@
     "js-yaml": "^3.3.1",
     "json-loader": "^0.5.2",
     "markdown-it": "^4.2.1",
-    "markdown-it-anchor": "^2.0.0",
-    "markdown-it-table-of-contents": "^0.1.2",
-    "markdown-it-toc": "^1.1.0",
     "markdown-it-toc-and-anchor": "^1.0.1",
     "metalsmith": "segmentio/metalsmith#wider-node-support",
     "metalsmith-collections": "^0.7.0",