Broken links in docs/guides/applications/messaging/install-mastodon-on-ubuntu-1604

[nmelehan-akamai]

In Installing a Mastodon Server on Ubuntu 16.04:

In the linked docker-compose file: https://www.linode.com/docs/guides/install-mastodon-on-ubuntu-1604/docker-compose.yml

These external links are broken and should be removed, as they pose a security risk:
https://github.com/usbsnowcrash/docker-privoxy.git
https://github.com/usbsnowcrash/docker-tor.git

GitHub:
https://github.com/linode/docs/blob/develop/docs/guides/applications/messaging/install-mastodon-on-ubuntu-1604/docker-compose.yml#L94