Write a VitePress docs page: How to build a custom ForgeKit template

[SubhanshuMG]

Summary

Write a documentation page explaining how to build a custom template that can be loaded via forgekit new --template github:owner/repo.

Location

docs/templates/custom.md

Content to cover

1. The forgekit.json manifest format
2. File structure with Handlebars variables ({{name}}, {{description}})
3. How to test your template locally
4. How to publish to GitHub and load it with github:owner/repo
5. How to publish to npm and load with npm:package-name

Acceptance criteria

• Page added to docs/templates/custom.md
• Linked from docs/templates/index.md
• Linked from VitePress sidebar in docs/.vitepress/config.ts