Add connection instructions for Flutter app (#96)

Added instructions for connecting to a running Flutter app using the
Dart Tooling Daemon.

fixes #94

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: johnpryan

README.md

@@ -115,6 +115,32 @@ This extension enforces a specific set of coding standards to ensure consistency
 - **`flutter.md`**: Contains rules and best practices for writing Dart and Flutter code. These rules are opinionated, and we encourage you to review them to ensure they align with your style.
 - **`override`**: Contains important, high-priority rules that are appended to the end of all prompts to ensure they have the most weight.
 
+## Connecting to a running app
+You can connect to an app by providing the Flutter extension with the URL for
+the Dart Tooling Daemon:
+
+1. **Run the app**: in VSCode on a target device (iOS, Android, macOS, or web)
+2. **Execute the Copy DTD Uri action**: Open the VSCode Command Runner
+(Cmd+Shift+P, or Ctrl+Shift+P) and type "Copy DTD Uri to Clipboard" to copy the
+DTD URL to your clipboard
+3. **Paste the URL into Gemini CLI**: Enter a prompt like "Connect to the
+Flutter app with this DTD URL: " and paste the URL from your clipboard. You
+should see a "Connection succeeded" message from the
+connect_dart_tooling_daemon MCP tool.
+
+Alternatively, you can run from the command line with the `--print-dtd` flag:
+
+```
+$ flutter run --print-dtd
+...
+The Dart Tooling Daemon is available at: ws://127.0.0.1:52636/M3G9d1Q3hFk=
+```
+
+To learn more about the Dart and Flutter MCP server, see the
+[Dart and Flutter MCP server](https://dart.dev/tools/mcp-server)
+page on dart.dev or the
+[dart_mcp_server README](https://github.com/dart-lang/ai/tree/main/pkgs/dart_mcp_server).
+
 ## Known issues
 
 * Running a Flutter app from within Gemini CLI and then triggering a Hot Reload