Add an alert for user-code so that it's more obvious

Author: intitni

Copilot for Xcode/CopilotView.swift

@@ -11,6 +11,7 @@ struct CopilotView: View {
     @State var userCode: String?
     @State var version: String?
     @State var isRunningAction: Bool = false
+    @State var isUserCodeCopiedAlertPresented = false
 
     var body: some View {
         Section {
@@ -25,6 +26,13 @@ struct CopilotView: View {
                         Button("Refresh") { checkStatus() }
                         if copilotStatus == .notSignedIn {
                             Button("Sign In") { signIn() }
+                                .alert(isPresented: $isUserCodeCopiedAlertPresented) {
+                                    Alert(
+                                        title: Text(userCode ?? ""),
+                                        message: Text("The user code is pasted into your clipboard, please paste it in the opened website to login.\nAfter that, click \"Confirm Sign-in\" to finish."),
+                                        dismissButton: .default(Text("OK"))
+                                    )
+                                }
                             Button("Confirm Sign-in") { confirmSignIn() }
                         }
                         if copilotStatus == .ok || copilotStatus == .alreadySignedIn || copilotStatus == .notAuthorized {
@@ -89,6 +97,7 @@ struct CopilotView: View {
                 pasteboard.setString(userCode, forType: NSPasteboard.PasteboardType.string)
                 message = "Usercode \(userCode) already copied!"
                 openURL(url)
+                isUserCodeCopiedAlertPresented = true
             } catch {
                 message = error.localizedDescription
             }

Copilot for Xcode/InstructionView.swift

@@ -15,7 +15,7 @@ Text("""
 1. Install Node.
 2. Click `Set Up Launch Agent` to set up an XPC service to run in the background.
 3. Refresh Copilot status or restart the app.
-4. Click `Sign In` to sign into your GitHub Account.
+4. Click `Sign In` to sign into your GitHub account. 
 5. After submitting your user code to the verification website, click `Confirm Sign-in` to finish the sign-in.
 6. Go to `Settings.app > Privacy & Security > Extension > Xcode Source Editor Extension` to turn **Copilot for Xcode** on.
 7. Restart Xcode, the Copilot commands should be available in the menu bar.