gitlab-ci: Add docbook job for WSUG and WSDG

Adds job of building the HTML versions of the
Wireshark User Guide and Wireshark Developer Guide.
PDF versions are not built because it would take significantly longer
(~10 mins instead of ~5 minutes)

.gitlab-ci.yml

@@ -148,6 +148,34 @@ test:debian-stable:
   dependencies:
     - build:debian-stable
 
+# Build Wireshark manuals
+# Note: Need ubuntu:focal with `ruby-coderay` and `ruby-asciidoctor-pdf` packages to build PDF docs
+docbook:
+  stage: build
+  image: wireshark/wireshark-ubuntu-dev
+  rules:
+    - changes:
+      - "docbook/**"
+      - "epan/wslua/**"
+  before_script:
+    - DEBIAN_FRONTEND="noninteractive" ./tools/debian-setup.sh --install-optional -y g++
+  script:
+    - mkdir build
+    - cd build
+    - cmake -GNinja ..
+    - ninja all_guides
+  after_script:
+    - mv build/docbook/wsug_html/ .
+    - mv build/docbook/wsug_html_chunked/ .
+    - mv build/docbook/wsdg_html/ .
+    - mv build/docbook/wsdg_html_chunked/ .
+  artifacts:
+    paths:
+      - wsug_html/
+      - wsug_html_chunked/
+      - wsdg_html/
+      - wsdg_html_chunked/
+
 # https://docs.gitlab.com/ee/user/gitlab_com/index.html#linux-shared-runners
 
 merge-req:commit-checks: