docs: added valid options for mm config

offset_syncs_topic_location takes a string of "source" or "target" but
the docs did not reflect that. The config also lacks a default and that
was not captured. This adds the valid options and the lack of a default

docs/resources/mirrormaker_replication_flow.md

@@ -38,7 +38,7 @@ resource "aiven_mirrormaker_replication_flow" "f1" {
 ### Required
 
 - `enable` (Boolean) Enable of disable replication flows for a service.
-- `offset_syncs_topic_location` (String) Offset syncs topic location.
+- `offset_syncs_topic_location` (String) Offset syncs topic location. Possible values are `source` & `target`. There is no default value. 
 - `project` (String) The name of the project this resource belongs to. To set up proper dependencies please refer to this variable as a reference. Changing this property forces recreation of the resource.
 - `replication_policy_class` (String) Replication policy class. The possible values are `org.apache.kafka.connect.mirror.DefaultReplicationPolicy` and `org.apache.kafka.connect.mirror.IdentityReplicationPolicy`. The default value is `org.apache.kafka.connect.mirror.DefaultReplicationPolicy`.
 - `service_name` (String) The name of the project this resource belongs to. To set up proper dependencies please refer to this variable as a reference. Changing this property forces recreation of the resource.

internal/sdkprovider/service/kafka/mirrormaker_replication_flow.go

@@ -104,7 +104,7 @@ var aivenMirrorMakerReplicationFlowSchema = map[string]*schema.Schema{
 	"offset_syncs_topic_location": {
 		Type:         schema.TypeString,
 		Required:     true,
-		Description:  "Offset syncs topic location.",
+		Description:  "Offset syncs topic location. Possible values are `source` & `target`. There is no default value.",
 		ValidateFunc: validation.StringInSlice([]string{"source", "target"}, false),
 	},
 }