doc: build infodocs target on Gitlab CI, Azure

Add infodocs target to CI testing.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 8d981a3..398fa2b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -149,14 +149,15 @@
     # search for HACK within source tree and ignore HACKKIT board
     - grep -r HACK . | grep -v HACKKIT
 
-# build HTML documentation
-htmldocs:
+# build documentation
+docs:
   stage: testsuites
   script:
     - virtualenv -p /usr/bin/python3 /tmp/venvhtml
     - . /tmp/venvhtml/bin/activate
     - pip install -r doc/sphinx/requirements.txt
     - make htmldocs
+    - make infodocs
 
 # some statistics about the code base
 sloccount: