README.md in zache-0.1.0 vs README.md in zache-0.2.0

@@ -19,9 +19,17 @@
 require 'zache'
 zache = Zache.new
 # Expires in 5 minutes
 v = zache.get(:count, lifetime: 5 * 60) { expensive() }
 ```
+
+By default `Zache` is thread-safe. You turn that off by using `sync` argument:
+
+```ruby
+zache = Zache.new(sync: false)
+v = zache.get(:count) { expensive() }
+```
+
 That's it.
 
 # How to contribute
 
 Read [these guidelines](https://www.yegor256.com/2014/04/15/github-guidelines.html).