refactor: move <fieldset> out of demo files

[elmariofredo]

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

[ ] bug report => search github for a similar issue or PR before submitting
[x] feature request
[ ] support request => You can submit support request here, but we preffer to chat about it realtime at our [ngParty slack](https://ngparty.herokuapp.com/)

Current behavior
we have fieldset in each demo files

Expected behavior
let's have it generated in in index.packge.html

What is the motivation / use case for changing the behavior?

clean demo files and allow work with element without fieldset clutter

[Hotell]

this is not a feature request