Fix wrong docs references (#79)

docs/machine-learning/datasets/demo/glass.md

@@ -21,9 +21,9 @@ Samples per class:
 To load Glass dataset simple use:
 
 ```
-use Phpml\Dataset\Demo\Glass;
+use Phpml\Dataset\Demo\GlassDataset;
 
-$dataset = new Glass();
+$dataset = new GlassDataset();
 ```
 
 ### Several samples example

docs/machine-learning/datasets/demo/iris.md

@@ -14,9 +14,9 @@ Most popular and widely available dataset of iris flower measurement and class n
 To load Iris dataset simple use:
 
 ```
-use Phpml\Dataset\Demo\Iris;
+use Phpml\Dataset\Demo\IrisDataset;
 
-$dataset = new Iris();
+$dataset = new IrisDataset();
 ```
 
 ### Several samples example

docs/machine-learning/datasets/demo/wine.md

@@ -14,9 +14,9 @@ These data are the results of a chemical analysis of wines grown in the same reg
 To load Wine dataset simple use:
 
 ```
-use Phpml\Dataset\Demo\Wine;
+use Phpml\Dataset\Demo\WineDataset;
 
-$dataset = new Wine();
+$dataset = new WineDataset();
 ```
 
 ### Several samples example