AxisVela Open v0.2.0

AxisVela Open v0.2.0

Publication and discovery release for the AxisVela Open documentation and project
index.

Added

• Site-wide language selector for English and Chinese.
• Documentation versioning page, including how documentation tags relate to
  product versions.
• Changelog and roadmap pages.
• CITATION.cff for machine-readable citation.
• robots.txt for crawlers.

Sites

• English: https://axisvela.github.io/axisvela-open/
• 中文: https://axisvela.github.io/axisvela-open/zh/

This tag versions the documentation and index, not the individual projects. See
CHANGELOG.md
for details.