OSDOCS-3643: Added Melbourne, Australia (australia-southeast2) to support GCP regions

Author: mjpytlak

modules/installation-gcp-regions.adoc

@@ -19,6 +19,7 @@ regions:
 * `asia-southeast1` (Jurong West, Singapore)
 * `asia-southeast2` (Jakarta, Indonesia)
 * `australia-southeast1` (Sydney, Australia)
+* `australia-southeast2` (Melbourne, Australia)
 * `europe-central2` (Warsaw, Poland)
 * `europe-north1` (Hamina, Finland)
 * `europe-west1` (St. Ghislain, Belgium)