Update database host references from 'secondary' to 'standby' in documentation and examples (#752)

Author: zliang-akamai

docs/modules/database_list.md

@@ -62,7 +62,7 @@ List and filter on Linode Managed Databases.
               "engine": "mysql",
               "hosts": {
                  "primary": "lin-123-456-mysql-mysql-primary.servers.linodedb.net",
-                 "secondary": "lin-123-456-mysql-primary-private.servers.linodedb.net"
+                 "standby": "lin-123-456-mysql-primary-private.servers.linodedb.net"
               },
               "id": 123,
               "instance_uri": "/v4/databases/mysql/instances/123",

docs/modules/database_mysql_info.md

@@ -51,7 +51,7 @@ Get info about a Linode MySQL Managed Database.
           "engine": "mysql",
           "hosts": {
             "primary": "lin-123-456-mysql-mysql-primary.servers.linodedb.net",
-            "secondary": "lin-123-456-mysql-primary-private.servers.linodedb.net"
+            "standby": "lin-123-456-mysql-primary-private.servers.linodedb.net"
           },
           "id": 123,
           "label": "example-db",

docs/modules/database_postgresql_info.md

@@ -51,7 +51,7 @@ Get info about a Linode PostgreSQL Managed Database.
           "engine": "postgresql",
           "hosts": {
             "primary": "lin-0000-000-pgsql-primary.servers.linodedb.net",
-            "secondary": "lin-0000-000-pgsql-primary-private.servers.linodedb.net"
+            "standby": "lin-0000-000-pgsql-primary-private.servers.linodedb.net"
           },
           "id": 123,
           "label": "example-db",

plugins/module_utils/doc_fragments/database_list.py

@@ -21,7 +21,7 @@
       "engine": "mysql",
       "hosts": {
          "primary": "lin-123-456-mysql-mysql-primary.servers.linodedb.net",
-         "secondary": "lin-123-456-mysql-primary-private.servers.linodedb.net"
+         "standby": "lin-123-456-mysql-primary-private.servers.linodedb.net"
       },
       "id": 123,
       "instance_uri": "/v4/databases/mysql/instances/123",

plugins/module_utils/doc_fragments/database_mysql.py

@@ -11,7 +11,7 @@
   "engine": "mysql",
   "hosts": {
     "primary": "lin-123-456-mysql-mysql-primary.servers.linodedb.net",
-    "secondary": "lin-123-456-mysql-primary-private.servers.linodedb.net"
+    "standby": "lin-123-456-mysql-primary-private.servers.linodedb.net"
   },
   "id": 123,
   "label": "example-db",

plugins/module_utils/doc_fragments/database_postgresql.py

@@ -11,7 +11,7 @@
   "engine": "postgresql",
   "hosts": {
     "primary": "lin-0000-000-pgsql-primary.servers.linodedb.net",
-    "secondary": "lin-0000-000-pgsql-primary-private.servers.linodedb.net"
+    "standby": "lin-0000-000-pgsql-primary-private.servers.linodedb.net"
   },
   "id": 123,
   "label": "example-db",