[DOCS] Remove reference to f:if viewhelper (#1039)

It doesn't make much sense from f:variable...

Author: linawolf

Documentation/ViewHelpers/Fluid.json

@@ -29,7 +29,6 @@
  *     {oldvariable -> f:format.htmlspecialchars() -> f:variable(name: 'newvariable')}
  *     <f:variable name="myvariable"><f:format.htmlspecialchars>{oldvariable}</f:format.htmlspecialchars></f:variable>
  *
- * @see \TYPO3Fluid\Fluid\ViewHelpers\IfViewHelper
  * @api
  */
 class VariableViewHelper extends AbstractViewHelper