added build/deploy

.gitlab-ci.yml

-before_script:
-  - cd docs
+stages:
+  - build
+  - deploy
 
-doc:
+build:
+  stage: build
+  before_script:
+    - cd docs
   script:
     -  nix-shell -p python3Packages.sphinx python3Packages.numpydoc python3Packages.pnam --run "make html"
+
+deploy:
+  stage: deploy
+  script:
     -  rsync -av _build/html/ /var/www/num/proxtoolbox/