fix JavaScript heap out of memory

NativeScript/nativescript-dev-webpack#458 (comment)

Author: afc163

package.json

@@ -90,7 +90,7 @@
     "preinstall": "npm run scaffold-install",
     "build-site": "rm -rf _site && npm run bisheng-build",
     "gh-pages": "gh-pages -d _site",
-    "site": "npm run build-site && npm run gh-pages",
+    "site": "cross-env NODE_OPTIONS=--max-old-space-size=4096 npm run build-site && npm run gh-pages",
     "components-publish": "./tool/bin/let -c && cd ./config/components && npm publish",
     "components-build": "./tool/bin/let -c && cd ./config/components",
     "clean": "rm -rf node_modules && cd ./scaffold && rm -rf node_modules",