internal: small CONTRIBUTING.md fixes

Change-Id: Id40d44d175a96a71985fe6cebe5f159de482b756
Reviewed-on: https://code-review.googlesource.com/c/34151
Reviewed-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

CONTRIBUTING.md

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 9db3f83..3b8c4d2 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -77,7 +77,7 @@
 $ gcloud auth login
 
 # Create the indexes used in the datastore integration tests.
-$ gcloud preview datastore create-indexes datastore/testdata/index.yaml
+$ gcloud datastore create-indexes datastore/testdata/index.yaml
 
 # Create a Google Cloud storage bucket with the same name as your test project,
 # and with the Stackdriver Logging service account as owner, for the sink
@@ -95,13 +95,15 @@
 
 # For Storage integration tests:
 # Enable KMS for your project in the Cloud Console.
+$ export MY_KEYRING=some-keyring-name
+$ export MY_LOCATION=us-east1
 # Create a KMS keyring, in the same location as the default location for your project's buckets.
-$ gcloud kms keyrings create MY_KEYRING --location MY_LOCATION
+$ gcloud kms keyrings create $MY_KEYRING --location $MY_LOCATION
 # Create two keys in the keyring, named key1 and key2.
-$ gcloud kms keys create key1 --keyring MY_KEYRING --location MY_LOCATION --purpose encryption
-$ gcloud kms keys create key2 --keyring MY_KEYRING --location MY_LOCATION --purpose encryption
+$ gcloud kms keys create key1 --keyring $MY_KEYRING --location $MY_LOCATION --purpose encryption
+$ gcloud kms keys create key2 --keyring $MY_KEYRING --location $MY_LOCATION --purpose encryption
 # As mentioned above, set the GCLOUD_TESTS_GOLANG_KEYRING environment variable.
-$ export GCLOUD_TESTS_GOLANG_KEYRING=projects/$GCLOUD_TESTS_GOLANG_PROJECT_ID/locations/MY_LOCATION/keyRings/MY_KEYRING
+$ export GCLOUD_TESTS_GOLANG_KEYRING=projects/$GCLOUD_TESTS_GOLANG_PROJECT_ID/locations/$MY_LOCATION/keyRings/$MY_KEYRING
 # Authorize Google Cloud Storage to encrypt and decrypt using key1.
 gsutil kms authorize -p $GCLOUD_TESTS_GOLANG_PROJECT_ID -k $GCLOUD_TESTS_GOLANG_KEYRING/cryptoKeys/key1
 ```