Bump version to 2.0.0, add note in readme about deprecation

Author: Nick Campbell

CHANGELOG.md

@@ -1,6 +1,7 @@
-# Unreleased
+# 2.0.0 / 2017-08-23
 
 - [#23](https://github.com/gocardless/activerecord-safer_migrations/pull/23) Drop support for Rails 4.0 and 4.1
+- [#24](https://github.com/gocardless/activerecord-safer_migrations/pull/24) Drop support for Ruby 2.0 and 2.1, add Ruby 2.4
 
 # 1.0.0 / 2016-05-09
 

README.md

@@ -1,5 +1,7 @@
 ## ActiveRecord safer migration helpers
 
+> Looking for Rails 4.0 or Ruby 2.0 support? Please check out the [1.x tree](https://github.com/gocardless/activerecord-safer_migrations/tree/v1.0.0).
+
 *Note: this library only supports PostgreSQL 9.3+. If you're interested in adding support for other databases, we're open to pull requests!*
 
 Postgres holds ACCESS EXCLUSIVE locks for [almost all][pg-alter-table] DDL