posts: ts219p2+ debian install

Short post covering the Exact Steps(tm) to install Debian on this nice
little NAS.

Signed-off-by: Michael Turquette <mturquette@deferred.io>
posts: ts219p2+ booting mainline linux

Placeholder for the final post in this series. Needs to be squashed
before publishing.

Signed-off-by: Michael Turquette <mturquette@deferred.io>