QtAA: Add "documentation-warnings" config

Starting from 6.9 the "ubuntu-22.04-documentation-x11-tests" config
was replaced by "ubuntu-22.04-developer-build-x11-tests". The new
configuration doesn't test the documentation for warnings which is
why we had failures in 6.8 where to docs were checked but not in 6.9
or dev.

This commit fixes the issue by adding the relatively new
"documentation-warnings" configuration, which will once again check
our documentation.

See also 434e4a224a .

Task-number: QAA-2878
Change-Id: I479a9606ab16f8b87009d26ab03636c4c658fcb5
Reviewed-by: Liang Qi <liang.qi@qt.io>
Reviewed-by: Jukka Jokiniva <jukka.jokiniva@qt.io>
(cherry picked from commit ea1abd55ce)
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>
(cherry picked from commit f95d6b1fdb)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

coin/platform_configs/tqtc-android-automotive.yaml

@@ -1,6 +1,7 @@
 Version: 2
 Include: [
     cmake_platforms.yaml: [
+        "documentation-warnings",
         "rhel-8.10",
         'windows-10_22h2-mingw13',
         'ubuntu-22.04-developer-build',