[ACME DEMO BUNDLE] Link to contact form

| Q             | A
| ------------- | ---
| Bug fix?      | [no]
| New feature?  | [yes]
| BC breaks?    | [no]
| Deprecations? | [no]
| Tests pass?   | [yes]
| Fixed tickets | [n/a]
| License       | MIT

Add link to contact form in the demo bundle.  Show the code how the contact form is rendered.

I am not sure from which version the contact is added. In case I need to send to a specific version / branch let me know .

Thanks!