add information about keyboard shortcuts

README.md

@@ -5,6 +5,7 @@ This is a quick drop-in CSS switcher to allow for previewing some of the many mi
 This project only includes _minimal_ frameworks, in other words, boilerplate frameworks that require no adjustment of the corresponding HTML and can be simply dropped into the project to provide a starting point for further design. No additional javascript, compiling, pre-processors, or fiddling with classes should be required for these to look good and be responsive.
 
 * [1 Usage](#usage)
+  * [1.1 Keyboard shortcut](#keyboard-shortcut)
 * [2 Frameworks](#frameworks)
   * [2.1 Adding frameworks](#adding-frameworks)
   * [2.2 List of frameworks](#list-of-frameworks)
@@ -22,6 +23,10 @@ To use the CSS switcher, just add the following line anywhere within the body ta
 
 That's it! You should now be able to cycle through the different frameworks by choosing them from the dropdown at the top of the page.
 
+### Keyboard shortcut
+
+You can quickly switch between frameworks by pressing the [modifier key or keys on your keyboard](https://github.com/dohliam/xsampa#access-keys) + `s` to focus the switcher dropdown menu, followed by the up and down keys to move up and down the list.
+
 ## Frameworks
 
 ### Adding frameworks