Add link to Github release page for downloading stable releases.

Henrik Ingo · Henrik Ingo · commit ba1fe7f6d6eb · 2017-12-01T21:48:16.000+02:00
Intentionally omitting git checkout &lt;tag&gt; alternative for simplicity.
Those that now how git works, will know it anyway.
diff --git a/README.md b/README.md
@@ -21,6 +21,11 @@ HOW TO USE IT
 
 Note: For a minimal checkout, omit the `--recursive` option. This will leave out extra plugins.
 
+**Stable releases**
+
+New features and fixes are continuously merged into the master branch, which is what the above command will check out. For the latest stable release, see the [Github Releases page](https://github.com/impress/impress.js/releases).
+
+
 ### Documentation
 
 
