Only index.html in dist folder?

### Issue type

**I'm submitting a ...** (check one with "x")

* [ ] bug report
* [ ] feature request
* [x] question ~about the decisions made in the repository~

### Issue description

**Current behavior:**

When I run ``npm run build:prod`` there's only index.html in the "dist" folder.
When I start a webserver via xampp, then it only shows the spinner like when you load the live-demo.

**Expected behavior:**

I expected that all html files (dashboard, forms, etc) are in the dist folder.

**Steps to reproduce:**

git clone
cd ngx-admin
npm i
npm run build:prod

### Other information:

**npm, node, OS, Browser**
```
$ node --version
v12.13.1

$ npm --version
6.12.1
```

**Angular, Nebular**
```
"@angular/animations": "^8.0.0",
"@angular/cdk": "^8.0.0",
"@angular/common": "^8.0.0",
"@angular/compiler": "^8.0.0",
"@angular/core": "^8.0.0",
"@angular/forms": "^8.0.0",
"@angular/platform-browser": "^8.0.0",
"@angular/platform-browser-dynamic": "^8.0.0",
"@angular/router": "^8.0.0",
"@nebular/auth": "4.4.0",
"@nebular/eva-icons": "4.4.0",
"@nebular/security": "4.4.0",
"@nebular/theme": "4.4.0",
```