Add link of the media-scanner to the download page

[michalramus]

Hello,
Since CasparCG for Linux is now distributed as separate .deb packages for Ubuntu (the server in one repository and the media-scanner in another), it can be confusing that the media-scanner is not linked on the download page.

Could you please add a link to the media-scanner release on the download page as well? This would make the Linux installation process clearer and easier to follow.

Thank you!