Add privacy policy

[natsteinmetz]

Add a page with a privacy policy. Link to it from the footer.

Possibly also create terms of use ?

Example policies;

• https://www.droidhood.org/privacy/
• https://alistapart.com/about/privacy-policy
• https://anitab.org/privacy-policy/
• https://anitab.org/terms-of-use/