copy fixes & adding a section

Author: dmolsen

README.md

@@ -137,6 +137,7 @@ You can also:
 
 * [Enable `dump()`](#enable-dump)
 * [Modify the Default Date and Interval Formats](#modify-the-default-date-and-interval-formats)
+* [Quickly disable extensions](#quickly-disable-extensions)
 
 ### Filters
 
@@ -159,7 +160,7 @@ $filter = new Twig_SimpleFilter('rot13', function ($string) {
 ?>
 ```
 
-Would be used like this in a pattern:
+This filter would be used like this in a pattern:
 
 ```twig
 {{ bar|rot13 }}
@@ -186,7 +187,7 @@ $function = new Twig_SimpleFunction('boo', function ($string) {
 ?>
 ```
 
-Would be used like this in a pattern:
+This function would be used like this in a pattern:
 
 ```twig
 {{ boo("ghost says what?") }}
@@ -218,7 +219,7 @@ $test = new Twig_SimpleTest('red', function ($value) {
 ?>
 ```
 
-Would be used like this in a pattern:
+This test would be used like this in a pattern:
 
 ```twig
 {% if shirt is red %}
@@ -308,7 +309,7 @@ if (!class_exists("Project_setdupe_TokenParser")) {
 ?>
 ```
 
-Would be used like this in a pattern:
+This tag would be used like this in a pattern:
 
 ```
 {% setdupe name = "Ziggy" %}
@@ -323,6 +324,20 @@ To use `dump()` set `twigDebug` in `config/config.yml` to `true`.
 
 You can modify the default date and interval formats for Twig by editing the `twigDefaultDateFormat` and `twigDefaultIntervalFormat` in `config/config.yml`. Set them to an empty string to use Twig's default formats. **Please note:** both must be set for this feature to work.
 
+### Quickly Disable Extensions
+
+To disable extensions that you're no longer using simply add an underscore to the beginning of a filename and then re-generate your site. For example, the enabled rot13 filter:
+
+    source/_twig-components/filters/rot13.filter.twig
+
+And the disabled rot13 filter:
+
+    source/_twig-components/filters/_rot13.filter.twig
+
+Then re-generate your Pattern Lab site with:
+
+    php core/console --generate
+
 ## Available Loaders
 
 If you're building a plugin that will be parsing Twig files you have access to three loaders. It's recommended that you use these instead of accessing Twig directly as these loaders will work with other PatternEngines.