Referencing Debian/Ubuntu directly for dkpg option on install page

[smythp]

When first hitting the installation page, I scanned for mentions of Debian and Ubuntu, and I only saw the dkpg curl option after heading to the releases page and getting the binary manually. Perhaps it might make sense to add a direct mention of Debian/Ubuntu to the comment line, or perhaps even to break out the curl commands into sections with headings? This may be less relevant if an aptitude package is planned for the future. This also might be useful for users who might have less familiarity with Linux packaging and binary conventions.

Encountered as friction in in #184 .