update readme and version bump

Author: bolandrm

CHANGELOG.md

@@ -1,3 +1,6 @@
+- **2.1.0.pre1**
+  - [Update Libsass to 3.6.0](https://github.com/sass/sassc-ruby/pull/96/files)
+  - [Support old Ruby versions](https://github.com/sass/sassc-ruby/pull/117/files)
 - **2.0.1**
   - [Relax FFI dependency](https://github.com/sass/sassc-ruby/pull/102)
 - **2.0.0**

README.md

@@ -6,7 +6,7 @@ This gem combines the speed of `libsass`, the [Sass C implementation](https://gi
 
 ### libsass Version
 
-[d225a09a](https://github.com/sass/libsass/commit/d225a09a152050d569c077f97bb944c8dc819d6f)
+[3.6.0](https://github.com/sass/libsass/releases/3.6.0)
 
 ## Installation
 

lib/sassc/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module SassC
-  VERSION = "2.0.1"
+  VERSION = "2.1.0.pre1"
 end