Fix validation dataset documentation to not use subsets

docs/flux_train_network.md

@@ -550,18 +550,32 @@ You can calculate validation loss during training using a validation dataset to
 To set up validation, add a `validation_split` and optionally `validation_seed` to your dataset configuration TOML file. 
 
 ```toml
+validation_seed = 42 # [Optional] Validation seed, otherwise uses training seed for validation split .
+
 [[datasets]]
 enable_bucket = true
 resolution = [1024, 1024]
-validation_seed = 42 # [Optional] Validation seed, otherwise uses training seed for validation split .
 
   [[datasets.subsets]]
   image_dir = "path/to/image/directory"
-  validation_split = 0.1 # Split between 0.0 and 1.0 where 1.0 will use the full subset as a validation dataset
+
+[[datasets]]
+enable_bucket = true
+resolution = [1024, 1024]
+validation_split = 0.1 # Split between 0.0 and 1.0 where 1.0 will use the full subset as a validation dataset
 
   [[datasets.subsets]]
+  # This directory will split 10% to validation and 90% to training
+  image_dir = "path/to/image/second-directory"
+
+[[datasets]]
+enable_bucket = true
+resolution = [1024, 1024]
+validation_split = 1.0 # Will use this full subset as a validation subset. 
+
+  [[datasets.subsets]]
+  # This directory will use the 100% to validation and 0% to training
   image_dir = "path/to/image/full_validation"
-  validation_split = 1.0 # Will use this full subset as a validation subset. 
 ```
 
 **Notes:**