samples: add samples README (#292)

Author: stephaniewang526

samples/README.md

@@ -0,0 +1,17 @@
+# Getting Started with BigQuery Samples
+
+## Running a sample using Cloud Shell
+
+The Google Cloud Shell has application default credentials from its compute instance which will allow you to run an integration test without having to obtain `GOOGLE_APPLICATION_CREDENTIANS`.
+
+However, certain samples require environment variables to be set. For instance, in `CreateDatasetIT.java`:
+
+`private static final String GOOGLE_CLOUD_PROJECT = System.getenv("GOOGLE_CLOUD_PROJECT");` - this sample integration test requires you to specific the [Google Cloud Project](https://cloud.google.com/resource-manager/docs/creating-managing-projects) you would like to run the test in.
+
+Make sure to set environment variables, if necessary, before running the sample, or else you will get an error asking you to set it.
+
+To run a samples integration tests in the cloud shell, simply run the following commands:
+
+`cd samples/snippets` - all samples are located in `java-bigquery/samples/snippets` directory.
+
+`mvn -Dtest=GetTableIT test` - this runs the integration test of `GetTable.java` sample.