Add header "Referrer-Policy: no-referrer"

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy

http/response/builder.go

@@ -97,6 +97,7 @@ func (b *Builder) writeHeaders() {
 	b.headers["X-Content-Type-Options"] = "nosniff"
 	b.headers["X-Frame-Options"] = "DENY"
 	b.headers["Content-Security-Policy"] = "default-src 'self'; img-src * data:; media-src *; frame-src *"
+	b.headers["Referrer-Policy"] = "no-referrer"
 
 	for key, value := range b.headers {
 		b.w.Header().Set(key, value)