Improve README (#532)

@jerjou's suggestions.

storage/storage-transfer/README.md

@@ -52,24 +52,20 @@ Creating a one-time transfer from Amazon S3 to Google Cloud Storage.
   1. Under Security Credentials, create an IAM User with access to the bucket.
   1. Create an Access Key for the user. Note the Access Key ID and Secret Access Key.
   1. Set the `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` environment variables.
-1. In AwsRequester.java, fill in the user-provided constants.
 1. Compile the package with
-
-```bash
-mvn compile
-```
-
+   ```bash
+   mvn compile
+   ```
 1. Run the transfer job with
-
-```bash
-mvn exec:java \
-   -Dexec.mainClass="com.google.cloud.storage.storagetransfer.samples.AwsRequester" \
-   -DprojectId=your-google-cloud-project-id \
-   -DjobDescription="Sample transfer job from S3 to GCS." \
-   -DawsSourceBucket=your-s3-bucket-name \
-   -DgcsSinkBucket=your-gcs-bucket-name
-```
-  1. Note the job ID in the returned Transfer Job.
+   ```bash
+   mvn exec:java \
+       -Dexec.mainClass="com.google.cloud.storage.storagetransfer.samples.AwsRequester" \
+       -DprojectId=your-google-cloud-project-id \
+       -DjobDescription="Sample transfer job from S3 to GCS." \
+       -DawsSourceBucket=your-s3-bucket-name \
+       -DgcsSinkBucket=your-gcs-bucket-name
+   ```
+   1. Note the job ID in the returned Transfer Job.
 
 ## Transfer data from a standard Cloud Storage bucket to a Cloud Storage Nearline bucket