router: Explain the return values of Lookup

router.go

diff --git a/router.go b/router.go
index ac3d680..4893950 100644
--- a/router.go
+++ b/router.go
@@ -270,6 +270,9 @@
 
 // Lookup allows the manual lookup of a method + path combo.
 // This is e.g. useful to build a framework around this router.
+// If the path was found, it returns the handle function and the path parameter
+// values. Otherwise the third return value indicates whether a redirection to
+// the same path with an extra / without the trailing slash should be performed.
 func (r *Router) Lookup(method, path string) (Handle, Params, bool) {
 	if root := r.trees[method]; root != nil {
 		return root.getValue(path)