Minor grammar fixes to documentation

doc/classes/Variant.xml

@@ -20,7 +20,7 @@
 		var boo = "Boo is a string!";
 		var ref = new RefCounted(); // var is especially useful when used together with a constructor.
 
-		// Godot also provides a Variant type that works like an union of all the Variant-compatible types.
+		// Godot also provides a Variant type that works like a union of all the Variant-compatible types.
 		Variant fooVar = 2; // fooVar is dynamically an integer (stored as a `long` in the Variant type).
 		fooVar = "Now fooVar is a string!";
 		fooVar = new RefCounted(); // fooVar is a GodotObject.