os.ReadDir

The os.ReadDir function resolves the path relative to the root of your project directory. A leading path separator (/) is optional.

With this directory structure:

content/
├── about.md
├── contact.md
└── news/
    ├── article-1.md
    └── article-2.md

This template code:

{{ range readDir "content" }}
  {{ .Name }} → {{ .IsDir }}
{{ end }}

Produces:

about.md → false
contact.md → false
news → true

Note that os.ReadDir is not recursive.

Details of the FileInfo structure are available in the Go documentation.