Document sphinx-multiversion workflow trigger requirements

[Copilot]

sphinx-multiversion builds all documentation versions (tags + branches) in a single pass by scanning git history. Both workflow triggers are required:

• Tag trigger: Rebuilds full docs when new versions are tagged
• Main branch trigger: Rebuilds full docs when development version changes
• fetch-depth: 0: Ensures full history access for version discovery

Changes

• .github/workflows/docs.yml: Added inline comments explaining trigger and fetch-depth requirements
• docs/README.md: Added comprehensive documentation on multiversion setup, why both triggers are essential, and local build instructions
• docs/source/conf.py: Added cross-reference comments to workflow documentation

Context

The workflow configuration was already correct but lacked documentation explaining why both triggers are necessary. Removing either trigger would result in incomplete or stale documentation builds, as sphinx-multiversion would only see partial git history.

Original prompt

Do i need to trigger on tag or on main branch only because im using sphinx-multiversion for building for multiple tags

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.