chore: improve messaging in func build (#562)

Fixes: https://github.com/knative-sandbox/kn-plugin-func/issues/552

Signed-off-by: Lance Ball <lball@redhat.com>

client.go

@@ -513,7 +513,7 @@ func (c *Client) Build(ctx context.Context, path string) (err error) {
 
 	m := []string{
 		"Still building",
-		"Don't give up",
+		"Don't give up on me",
 		"This is taking a while",
 		"Still building"}
 	ticker := time.NewTicker(5 * time.Second)

cmd/build.go

@@ -118,6 +118,7 @@ func runBuild(cmd *cobra.Command, _ []string, clientFn buildClientFn) (err error
 				}
 				return
 			}
+			fmt.Println("Note: building a Function the first time will take longer than subsequent builds")
 		}
 
 		// We have the registry, so let's use it to derive the Function image name