* Add README files to several directories in app/ giving a brief
overview of some parts of Danbooru's architecture.
* Add documentation for files in config/.
Bug: capistrano didn't update the crontab during deployment. As a result
the crontab still referenced an old deployment. Eventually that
deployment was deleted and cronjobs started silently failing.
Broken in 223e5f1e8. Turns out that `whenever` defaults to running on
servers with the `db` role. Removing kagamihara from the db role meant
that whenever was no longer configured to run anywhere.
Upgrade procedure:
$ echo 2.6.3 > .ruby-version
# upgrade ruby-build to know about the latest ruby versions.
# see also: github.com/rkh/rbenv-update
$ cd ~/.rbenv/plugins/ruby-build && git pull
# install the version of ruby specified in .ruby-version.
# see also: github.com/capistrano/rbenv/issues/83
$ rbenv install --skip-existing
# update the shell to use the latest version of ruby by default.
$ rbenv global 2.6.3
# update rubygems and bundler
$ gem update --system
# update the lockfile to use the latest version of bundler
$ bundle update --bundler
