Fixes typo in installer options

This typo caused the accessmode for gce storage to not be set.

Author: jmckulk

installers/kubectl/postgres-operator.yml

@@ -285,7 +285,7 @@ spec:
                     value: "alternatesite"
                   - name: STORAGE8_NAME
                     value: "gce"
-                  - name: STORAGE8_ACCESS
+                  - name: STORAGE8_ACCESS_MODE
                     value: "ReadWriteOnce"
                   - name: STORAGE8_SIZE
                     value: "300M"