Edited Asset helper documentation

Author: weierophinney

doc/book/helpers/asset.md

@@ -1,13 +1,18 @@
 # Asset
 
-The `Asset` helper is used to translate asset names.
-It could be used to prevent browser caching for assets.
+The `Asset` helper is used to map asset names to versioned assets.
+
+This can be used to allow using a single, canonical name for an asset within
+your view scripts, while having that map to:
+
+- A versioned asset name, used to prevent browser caching.
+- A product of a build process (such as a CSS pre-processor, JS compiler, etc.)
 
 ## Configuration and Basic Usage
 
-`Zend\View\Helper\Service\AssetFactory` checks the application
-configuration, making it possible to set up the resource map through
-your `module.config.php`. The next example will set up `Asset` helper:
+`Zend\View\Helper\Service\AssetFactory` checks the application configuration,
+making it possible to set up the resource map through your `module.config.php`
+or application configuration. As an example:
 
 ```php
 'view_helper_config' => [
@@ -20,37 +25,35 @@ your `module.config.php`. The next example will set up `Asset` helper:
 ],
 ```
 
-Then in your view you can use:
+Within your view script, you would reference the asset name:
 
 ```php
 // Usable in any of your .phtml files:
 echo $this->asset('css/style.css');
 ```
 
-and you would receive following output:
+which then emits the following output:
 
 ```html
 css/style-3a97ff4ee3.css
 ```
 
-The first argument of the `asset` helper is the regular asset name,
-which will be replaced by versioned asset name defined in `resource_map`
-of the configuration.
+The first argument of the `asset` helper is the regular asset name, which will
+be replaced by the associated value defined in the `resource_map` of the
+configuration.
 
-> ### Note
+> ### Exceptions
 >
-> When `asset` key is defined but `resource_map` is not provided or is not
-> an array exception `Zend\View\Exception\RuntimeException` will be
-thrown.
+> When an `asset` key is specified but the `resource_map` is not provided or is not
+> an array, the helper will raise a `Zend\View\Exception\RuntimeException`.
 >
-> When you call `asset` helper with parameter which is not defined on your
-> `resource_map` exception `Zend\View\Exception\InvalidArgumentException`
-> will be thrown.
+> When you call the `asset` helper with a parameter not defined in your
+> `resource_map`, the helper will raise a `Zend\View\Exception\InvalidArgumentException`.
 
 ## Resource map in JSON file
 
-If you have JSON file with resource map, for example
-`rev-manifest.json`:
+A number of build tools, such as gulp-rev and grunt-rev, will create a JSON
+resource map file such as `rev-manifest.json`:
 
 ```javascript
 {
@@ -59,16 +62,17 @@ If you have JSON file with resource map, for example
 }
 ```
 
-then you can have in your configuration:
+You can incorporate these into your configuration manually by fetching and
+decoding the contents:
 
 ```php
 'view_helper_config' => [
     'asset' => [
-        'resource_map' => json_decode(file_get_contents('/path/to/rev-manifest.json'), true),
+        'resource_map' => json_decode(file_get_contents('path/to/rev-manifest.json'), true),
     ],
 ],
 ```
 
-and when you have enabled cache config this file will be also cached in
-compiled configuration cache, so it prevents reading the file on each
-page load.
+If you have enabled configuration caching, these values _will also be cached_,
+meaning that the above operation will occur exactly once in your production
+configuration.