add service worker info to README

Author: ascott1

README.md

@@ -30,7 +30,7 @@ bundle exec jekyll serve --watch --baseurl ''
 Open it up in your browser: <http://localhost:4000/>
 
 
-## _config.yml
+## `_config.yml`
 
 Options within the `_config.yml` file allow you to control the site's title, subtitle, logo, author information, and the left column navigation.
 
@@ -48,6 +48,24 @@ Sometimes it's nice to preview your Jekyll site before you push your `gh-pages`
 
 This way, you can preview your site locally from the site root on localhost, but when GitHub generates your pages from the gh-pages branch all the URLs will start with `/project-name` and resolve properly.
 
+## Offline support
+
+By default DOCter provides offline support via a [Service Worker](http://www.html5rocks.com/en/tutorials/service-worker/introduction/). This means that after an initial load of your DOCter site, a cached version will be available offline in some modern browsers.
+
+**To disable offline caching:**
+
+in `_config.yml`: set `offline_cache` to false (defaults to true).
+
+**To update the cached version of your site:**
+
+in `_config.yml` change the value of `cache_name`
+
+**To add additional pages or files to the cache:**
+
+Update the `filesToCache` array in `sw.js`;
+
+
+
 ## License
 
 The project is in the public domain, and all contributions to it will be released as such. By submitting a pull request, you are agreeing to waive all rights to your contribution under the terms of the [CC0 Public Domain Dedication](http://creativecommons.org/publicdomain/zero/1.0/).