fix: repair broken admonitions caused by Docusaurus 3.10.1 upgrade

[Juminstock]

Summary

The Docusaurus 3.10.1 upgrade (#793) pulled in a newer mdast-util-directive/micromark-extension-directive. It enforces the strict directive spec: admonition titles must use bracket syntax, :::info[Title]. The old freeform syntax :::info Title is no longer recognized as a directive at all, so it silently rendered as literal paragraph text instead of a styled callout (as reported by Guenael on the Subsquare governance guide).

• Converted all freeform-title admonitions (:::type Title -> :::type[Title]) across the repo: 25 in subsquare_guide.md, 72 more across 18 other files.
• Removed two unrelated orphaned closing ::: fences (pre-existing since 2022/2023, unrelated to the dependency bump) in binary.md and docker.md that were also rendering as stray literal text.

[github-actions]

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