Merge pull request #119 from diazwatson/108_EnhancementForThisInTemplateDoc

#108 Enhance doc for ThisInTemplate rule

Author: lenaorobei

Diff for: Magento2/Sniffs/Templates/ThisInTemplateSniff.md

@@ -6,8 +6,32 @@ In PHTML templates, the current block is available as `$this` and `$block`. The
 `$this` in templates is a legacy from Magento 1. It still works, however this can change any time, should templates and blocks be further decoupled. That's why for new code you should always use `$block` and restrict it to public methods.
 
 ## How it works
-Any occurence of `$this` in PHTML files (via file pattern in ruleset.xml) raises a warning. 
+Any occurrence of `$this` in PHTML files (via file pattern in ruleset.xml) raises a warning. 
 
 ## How to fix
 
-Replace `$this` with `$block`. If you use private or protected methods, make them public.
+Replace `$this` with `$block`. If you use private or protected methods, make them public.
+
+---
+
+## Reasoning
+The use of helpers is in general discouraged therefore any `$this->helper(<helper_class>)` code used in PHTML templates should be refactored.
+
+Consider using ViewModel instead.
+
+## How to fix
+
+Typical example of a helper being used in a PHTML:
+```html
+<?php $_incl = $block->helper(<helper_class>)->...; ?>
+```
+
+Once the ViewModel is created, call it in the PHTML as follow:
+
+```html
+<?php $viewModel = $block->getViewModel(); ?>
+```
+or
+```html
+<?php $viewModel = $block->getData('viewModel'); ?>
+```