Ananke submodule update

Results: https://vrouvrea.gitlabpages.inria.fr/doc/branches/theme_ananke_update/

• github ananke submodule has changed
• Take latest ananke v.2.9.1
• Fix images that were taking 100% of the width
• Fix text to take 100% of the width
• Add localconfig.toml and readme explanations to serve the pages locally
• Fix gitlab-ci.yml to build docker images only when dockerfile is changed (was not working)