Add schema files to documentsearch package.

Also add them to the package template.

buildutils/template/package.json

@@ -10,6 +10,7 @@
   "author": "Project Jupyter",
   "files": [
     "lib/**/*.{d.ts,eot,gif,html,jpg,js,js.map,json,png,svg,woff2,ttf}",
+    "schema/*.json",
     "style/**/*.{css,eot,gif,html,jpg,json,png,svg,woff2,ttf}"
   ],
   "main": "lib/index.js",

packages/documentsearch-extension/package.json

@@ -10,6 +10,7 @@
   "author": "Project Jupyter",
   "files": [
     "lib/**/*.{d.ts,eot,gif,html,jpg,js,js.map,json,png,svg,woff2,ttf}",
+    "schema/*.json",
     "style/**/*.{css,eot,gif,html,jpg,json,png,svg,woff2,ttf}"
   ],
   "main": "lib/index.js",