docs: fix filepath of example command in README (#160)

Author: leahecole

packages/google-cloud-videointelligence/samples/README.md

@@ -50,7 +50,7 @@ Options:
 Examples:
   node analyze.js shots gs://demomaker/sushi.mp4
   node analyze.js labels-gcs gs://demomaker/tomatoes.mp4
-  node analyze.js labels-file cat.mp4
+  node analyze.js labels-file ./resources/cat.mp4
   node analyze.js safe-search gs://demomaker/tomatoes.mp4
   node analyze.js transcription gs://demomaker/tomatoes.mp4