MQE-2034: Document Custom Helper functionality

Author: tomreece

docs/custom-helpers.md

@@ -1,6 +1,6 @@
 # Custom Helpers
 
-Custom Helpers allow test writers to write custom test actions to solve for their advanced requirements beyond what MFTF offers out of the box.
+Custom Helpers allow test writers to write custom test actions to solve for advanced requirements beyond what MFTF offers out of the box.
 
 In MFTF version 3.0.0, we removed the following test actions:
 
@@ -20,9 +20,9 @@ Custom Helpers are implemented in PHP files that must be placed in this director
 
 Let's take a look at one. This Custom Helper selects text on the page by this approach:
 
-1. Move to a very specific X,Y starting value
+1. Move to a very specific X,Y starting position
 2. Click and hold the mouse button down
-3. Move to another specific X,Y value
+3. Move to another specific X,Y position
 4. Release the mouse button
 
 This functionality is used to select text on the page and cannot be accomplished using built-in test actions.
@@ -75,13 +75,13 @@ class SelectText extends Helper
 }
 ```
 
-### Important Notes About The PHP File
+### Notes About The PHP File
 
 The following details are important about the file above:
 1. The `namespace` must match the file location like `namespace Magento\PageBuilder\Test\Mftf\Helper;`
 2. The class must `extends Helper` and have the corresponding `use` statement to match
 3. You can get access to the WebDriver object via `$this->getModule('\Magento\FunctionalTestingFramework\Module\MagentoWebDriver')`
-4. You can implement multiple methods in the same class.
+4. You can implement multiple related methods in the same class.
 
 You should follow the same patterns in any Custom Helpers that you write yourself. But you can implement any logic or iteration that you need to solve for your use case.
 
@@ -99,7 +99,7 @@ Once you have implemented something like the above PHP file. You can then refere
 </helper>
 ```
 
-### Important Notes About The XML
+### Notes About The XML
 
 1. Specify an argument value for every argument that matches our PHP implementation. This allows us to pass other test data to the Custom Helper.
 2. The `class` attribute matches the namespace we specified in the PHP file
@@ -110,6 +110,12 @@ Once you have implemented something like the above PHP file. You can then refere
 
 Custom Helpers allow you to solve for complex use cases such as conditional logic, iteration, or complex WebDriver usage.
 
+With access to the WebDriver object, you have a lot of flexibility available to you. See the [Codeception WebDriver](https://github.com/Codeception/module-webdriver/blob/master/src/Codeception/Module/WebDriver.php) for technical details and functionality available for use.
+
 A Custom Helper is written in a PHP file and then referenced in test XML like other actions.
 
 Due to complexity, you should only use these as a last resort after trying to implement your test using built-in actions.
+
+## References
+
+[Codeception WebDriver source code](https://github.com/Codeception/module-webdriver/blob/master/src/Codeception/Module/WebDriver.php) - Reference for using the WebDriver Object