Add sample leaf template.

x509util/templates.go

@@ -0,0 +1,15 @@
+package x509util
+
+const DefaultLeafTemplate = `{
+	"subject": {{ toJson .Subject }},
+	"sans": [
+	{{- range $index, $san := initial .SANs }}
+		{"type": "{{ $san.Type }}", "value": "{{ $san.Value }}"},
+	{{- end }}
+	{{- with last .SANs }}
+		{"type": "{{ .Type }}", "value": "{{ .Value }}"}
+	{{- end }}
+	],
+	"keyUsage": ["keyEncipherment", "digitalSignature"],
+	"extKeyUsage": ["serverAuth", "clientAuth"]
+}`