fix(demo): fix build

Author: denStrigo

angular.json

@@ -220,7 +220,6 @@
               "optimization": true,
               "outputHashing": "all",
               "sourceMap": false,
-              "extractCss": true,
               "namedChunks": false,
               "extractLicenses": true,
               "vendorChunk": false,

package.json

@@ -28,7 +28,7 @@
     "e2e": "ng e2e",
     "docs": "compodoc -p src/tsconfig.app.json -d docs",
     "docs:dirs": "gulp create-docs-dirs",
-    "docs:prod": "npm run build -- docs --prod --aot --base-href /ngx-admin/",
+    "docs:prod": "npm run build -- docs --configuration production --aot --aot --base-href /ngx-admin/",
     "docs:build": "npm-run-all docs:prod docs:dirs",
     "docs:serve": "npm start -- docs --port 4100",
     "docs:gh-pages": "ts-node -P ./scripts/docs/tsconfig.json ./scripts/docs/build-docs.ts",