Upstream changes
- Merge branch 'feature/isset-to-null-coalescing-op' into 'master'
- Replace basic 'isset()' cases with the null coalescing operator.
- Merge branch 'master' of gitlab.tt-rss.org:tt-rss/tt-rss
- Merge branch 'weblate-integration' into 'master'
- Translated using Weblate (Spanish)
- set proper stages for phpdoc jobs
- copy docs to subpath
- set phpdoc image name
- add phpdoc dockerfile
- exp - use phpdoc container