Update README.md

Author: kilna-magento

README.md

@@ -47,9 +47,11 @@ If you would like to see if your lambda function builds properly, run:
 $ docker run example-lambda-image lambda build
 ```
 
-If you would like to get a ZIP file of the lambda function suitable for uploading to Amazon:
+If you would like to get a ZIP file of the lambda function suitable for uploading to Amazon, and the build log in one command:
 
 ```
-$ docker run example-lambda-image sh -c 'rm -rf dist* && lambda build 2&>1 >/dev/null && tar -c dist/*.zip' | tar -x -v
-dist/2017-08-31-212523-example-lambda.zip
+$ docker run example-lambda-image sh -c 'rm -rf build.log dist || true && lambda build &>build.log && tar -c build.log dist' | tar -x -v
+build.log
+dist/
+dist/2017-09-01-003647-example-lambda.zip
 ```