Merge branch 'ci' into 'master'

build PDF via CI

See merge request !4

.gitlab-ci.yml

+build:
+  image: ctornau/latex
+  stage: build
+  artifacts:
+    paths:
+      - standard.pdf
+  script:
+    - latexmk -shell-escape -pdf standard.tex

README.md

+# cats-standard
+
+This repository holds the CATS standard. There's no code here, other than LaTeX.
+
+[View the latest standard (PDF)](https://gitlab.scd31.com/cats/cats-standard/builds/artifacts/master/file/standard.pdf?job=build)