Rename documentation section + Update relative links

arkindex_worker/worker/element.py

arkindex_worker/worker/entity.py

arkindex_worker/worker/metadata.py

docs/contents/implem/configure.md

docs/contents/workers/ci/index.md

docs/contents/workers/create.md

docs/contents/workers/index.md

docs/contents/workers/maintenance.md

docs/contents/workers/template-structure.md

docs/ref/arkindex_workers.md

docs/releases.md

mkdocs.yml