message: Add a link to command substitution documentation
  Requested by
diff: @@ -37,7 +37,7 @@ Start quick debugging by running the *CMake: Debug Target* command from the VS
  You can specify the working directory or command line arguments for debugging, or use another debugger than the one included with Microsoft's `vscode-ms-vscode.cpptools`, by creating a `launch.json` file.
  -You'll need to know the path to the executable binary, which may be difficult to know in advance. CMake Tools can help by using command substitution in the `launch.json` file. This is already used by things like process selection when attaching to a running process. It works by specifying a command-based substitution in the appropriate field of `launch.json`.
  +You'll need to know the path to the executable binary, which may be difficult to know in advance. CMake Tools can help by using [command substitution](https://github.com/microsoft/vscode-cmake-tools/blob/develop/docs/cmake-settings.md#command-substitution) in the `launch.json` file. This is already used by things like process selection when attaching to a running process. It works by specifying a command-based substitution in the appropriate field of `launch.json`.
  Here is a minimal example of a `launch.json` file that uses `cmake.launchTargetPath` and `cmake.getLaunchTargetDirectory` to start a debugger on the active launch target:
  