OSDOCS-10419:adding two new support regions

Author: Brendan Daly

modules/installation-gcp-regions.adoc

@@ -10,6 +10,7 @@
 You can deploy an {product-title} cluster to the following Google Cloud Platform (GCP)
 regions:
 
+* `africa-south1` (Johannesburg, South Africa)
 * `asia-east1` (Changhua County, Taiwan)
 * `asia-east2` (Hong Kong)
 * `asia-northeast1` (Tokyo, Japan)
@@ -33,6 +34,7 @@ regions:
 * `europe-west9` (Paris, France)
 * `europe-west12` (Turin, Italy)
 * `me-central1` (Doha, Qatar, Middle East)
+* `me-central2` (Dammam, Saudi Arabia, Middle East)
 * `me-west1` (Tel Aviv, Israel)
 * `northamerica-northeast1` (Montréal, Québec, Canada)
 * `northamerica-northeast2` (Toronto, Ontario, Canada)