[gnome-shell/zbrown/docgen] ci: Build docs in CI

[Zander Brown <zbrown src gnome org>]

commit d9c15254460a21edc19a80bea58afdd8820c295d
Author: Zander Brown <zbrown gnome org>
Date:   Mon Jun 7 01:10:28 2021 +0100

    ci: Build docs in CI

 .gitlab-ci.yml | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 78f380aa41..c891adaacd 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -9,6 +9,7 @@ stages:
  - review
  - build
  - test
+ - docs
  - deploy
 
 default:
@@ -227,3 +228,31 @@ nightly:
   extends: '.publish_nightly'
   variables:
     BUNDLES: '$BUNDLE'
+
+reference:
+    stage: docs
+    needs: []
+    before_script:
+        - .gitlab-ci/checkout-mutter.sh
+        - meson mutter mutter/build --prefix=/usr -Dtests=false
+        - ninja -C mutter/build install
+    script:
+        - meson -Dman=false -Dgtk_doc=true _build
+        - ninja -C _build
+        - mkdir -p _reference/
+        - mv _build/docs/St/ _reference/
+        - mv _build/docs/Shell/ _reference/
+    artifacts:
+        paths:
+            - _reference
+
+pages:
+    stage: deploy
+    needs: ['reference']
+    script:
+        - mv _reference/ public/
+    artifacts:
+        paths:
+             - public
+    only:
+        - master