Update Spanner usage command text. (GoogleCloudPlatform#1449)

Author: jsimonweb

spanner/cloud-client/src/main/java/com/example/spanner/SpannerSample.java

@@ -1326,7 +1326,7 @@ static void printUsageAndExit() {
  System.err.println(" SpannerExample writeandreadusingdml my-instance example-db");
  System.err.println(" SpannerExample updateusingdmlwithstruct my-instance example-db");
  System.err.println(" SpannerExample writeusingdml my-instance example-db");
- System.err.println(" SpannerExample queryWithParameter my-instance example-db");
+ System.err.println(" SpannerExample querywithparameter my-instance example-db");
  System.err.println(" SpannerExample writewithtransactionusingdml my-instance example-db");
  System.err.println(" SpannerExample updateusingpartitioneddml my-instance example-db");
  System.err.println(" SpannerExample deleteusingpartitioneddml my-instance example-db");