gitlab-ci: rougify: append to main.scss

gitlab-ci: fix seq

gitlab-ci: make rouge style

posts: add docker-in-lxc

posts: add sendmail

config: remove location

pages: add cat and tag

post: add hello world

nav: add tags and cats

config: more customization

config: customize

gitlab-ci: parallel gem install

config: fix uri

gitlab-ci; fix encoding

Add .gitlab-ci.yml

Release 4.20.2 💎

Fix broken link in documentation

Close #2677

Fix typo

Close #2678

Bump copyright year

Update CHANGELOG and history