docs: mention templates in contributing section of README (#401)

Author: bcoe

packages/google-cloud-videointelligence/README.md

@@ -134,6 +134,8 @@ has instructions for running the samples.
 | Analyze_face_detection_gcs | [source code](https://github.com/googleapis/nodejs-video-intelligence/blob/master/samples/analyze_face_detection_gcs.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/nodejs-video-intelligence&page=editor&open_in_editor=samples/analyze_face_detection_gcs.js,samples/README.md) |
 | Analyze_person_detection | [source code](https://github.com/googleapis/nodejs-video-intelligence/blob/master/samples/analyze_person_detection.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/nodejs-video-intelligence&page=editor&open_in_editor=samples/analyze_person_detection.js,samples/README.md) |
 | Analyze_person_detection_gcs | [source code](https://github.com/googleapis/nodejs-video-intelligence/blob/master/samples/analyze_person_detection_gcs.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/nodejs-video-intelligence&page=editor&open_in_editor=samples/analyze_person_detection_gcs.js,samples/README.md) |
+| Detect_logo | [source code](https://github.com/googleapis/nodejs-video-intelligence/blob/master/samples/detect_logo.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/nodejs-video-intelligence&page=editor&open_in_editor=samples/detect_logo.js,samples/README.md) |
+| Detect_logo_gcs | [source code](https://github.com/googleapis/nodejs-video-intelligence/blob/master/samples/detect_logo_gcs.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/nodejs-video-intelligence&page=editor&open_in_editor=samples/detect_logo_gcs.js,samples/README.md) |
 | Quickstart | [source code](https://github.com/googleapis/nodejs-video-intelligence/blob/master/samples/quickstart.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/nodejs-video-intelligence&page=editor&open_in_editor=samples/quickstart.js,samples/README.md) |
 
 
@@ -164,6 +166,12 @@ More Information: [Google Cloud Platform Launch Stages][launch_stages]
 
 Contributions welcome! See the [Contributing Guide](https://github.com/googleapis/nodejs-video-intelligence/blob/master/CONTRIBUTING.md).
 
+Please note that this `README.md`, the `samples/README.md`,
+and a variety of configuration files in this repository (including `.nycrc` and `tsconfig.json`)
+are generated from a central template. To edit one of these files, make an edit
+to its template in this
+[directory](https://github.com/googleapis/synthtool/tree/master/synthtool/gcp/templates/node_library).
+
 ## License
 
 Apache Version 2.0