Merge branch 'ci' into 'master'

auto build pdf

See merge request !1

.gitlab-ci.yml

+stages:
+  - doc
+
+buildpdf:
+  stage: doc
+  image: debian:latest
+  script:
+    - apt-get update
+    - apt-get -y install pandoc texlive-base-bin texlive-latex-recommended texlive-fonts-recommended
+    - pandoc anleitung.md characters.md Raumbeschreibung.md -o piece-of-cake.pdf
+  artifacts:
+    paths:
+      - piece-of-cake.pdf
+    expire_in: 2 weeks
+  tags:
+    - docker