Add privacy and warranty information.

[Jo-Schie]

@svenb78 raised my attention to an important issue.

We should have information in the Validator tool that informs the user:

• privacy information: how is data stored, processed and used in the application (i.e. no presistent storage of information, everything run sin the browser.) + Link to Github Pages Privacy Information and short summary what they actually track.
• Warranty and copyright information (Link to Open Source Repo, Use at your own risk/no warranty).

[Jo-Schie]

fyi @mucke2701 and @ffischer1984