docs: consolidate recipe references

[wolfv]

Address the reference and navigation findings from the documentation review:

• add one canonical glob syntax page and link source, build, and package-content fields to it
• remove the contradictory duplicate glob explanation
• remove stale Git guidance and broken Jinja/environment links
• trim duplicated history and Jinja material from the recipe field reference
• fix the recipe reference heading hierarchy
• rename the navigation entry from "Multiple output cache" to "Staging outputs"

Validated with zensical build --strict and all 23 documentation recipe snippets.