Clarify comment

client.go

@@ -28,6 +28,7 @@ type Request struct {
 	URL *url.URL
 
 	// For client requests, Host specifies the host on which the URL is sought.
+	// Host must contain a port.
 	// This field is ignored by the server.
 	Host string
 

examples/client/client.go

@@ -47,7 +47,7 @@ func init() {
 	}
 }
 
-// sendRequest sends a request to the given url.
+// sendRequest sends a request to the given URL.
 func sendRequest(req *gmi.Request) error {
 	resp, err := client.Send(req)
 	if err != nil {

server.go

@@ -212,7 +212,7 @@ func InputHandler(prompt string) Handler {
 	})
 }
 
-// Redirect replies to the request with a redirect to the given url.
+// Redirect replies to the request with a redirect to the given URL.
 func Redirect(rw *ResponseWriter, req *Request, url string) {
 	rw.WriteHeader(StatusRedirect, url)
 }