Added missed limiters for Visual Shader node enums

doc/classes/VisualShaderNodeVectorOp.xml

@@ -52,5 +52,8 @@
 		<constant name="OP_STEP" value="11" enum="Operator">
 			Vector step operator. Returns [code]0.0[/code] if [code]a[/code] is smaller than [code]b[/code] and [code]1.0[/code] otherwise.
 		</constant>
+		<constant name="OP_ENUM_SIZE" value="12" enum="Operator">
+			Represents the size of the [enum Operator] enum.
+		</constant>
 	</constants>
 </class>