Allow specifying the output file in the YAML prefix

go/blog/blog.go

	NoDefaultStyle bool   `yaml:"no_default_style"`
	Title          string `yaml:"title"`
	After          string `yaml:"after"`
	// options only in the YAML prefix:
	Output string `yaml:"output"`
}
var flags struct {
				flags.After = opts.After
			}
		})
		// write to specified `output` file if none was given as an argument
		if opts.Output != "" && out == os.Stdout {
			out, err = os.Create(opts.Output)
			if err != nil {
				exit(err)
			}
		}
	}
	var posts []Post

go/blog/blog.yaml

title: A test blog
reverse: true
output: blog.html
---
- title: pacman -Qo $(ls -1t --time=atime /usr/bin | tail -n30)
  content: