add doc stage

.gitlab-ci.yml

@@ -4,6 +4,7 @@ default:
 
 stages:
   - build
+  - doc
   - pages
 
 cmake:
@@ -20,9 +21,9 @@ cmake:
         -DCMAKE_CXX_COMPILER=g++
 
 doc:
-  stage: build 
+  stage: doc 
   dependencies:
-    - cmake
+    - build
   artifacts:
     name: cpp_tools_doc
     expire_in: 1 day