update readme

Author: bolandrm

README.md

@@ -6,7 +6,7 @@ This gem combines the speed of `libsass`, the [Sass C implementation](https://gi
 
 ### libsass Version
 
-[3.3.0-beta3](https://github.com/sass/libsass/releases/tag/3.3.0-beta3)
+[3.3.0](https://github.com/sass/libsass/releases/tag/3.3.0)
 
 ## Usage
 
@@ -25,6 +25,8 @@ and [awesome contributors](https://github.com/bolandrm/sassc-ruby/graphs/contrib
 
 ## Changelog
 
+- **1.8.0**
+  - Update to Libsass 3.3.0
 - **1.8.0.pre2**
   - Fix bug with looking up gem_path
 - **1.8.0.pre1**