README.md in config-1.6.1 vs README.md in config-1.7.0

@@ -1,13 +1,12 @@
 # Config
 
 [![Build Status](https://api.travis-ci.org/railsconfig/config.svg?branch=master)](http://travis-ci.org/railsconfig/config)
 [![Gem Version](https://badge.fury.io/rb/config.svg)](http://badge.fury.io/rb/config)
 [![Dependency Status](https://gemnasium.com/railsconfig/config.svg)](https://gemnasium.com/railsconfig/config)
-[![Code Climate](https://codeclimate.com/github/railsconfig/config/badges/gpa.svg)](https://codeclimate.com/github/railsconfig/config)
-[![Issue Count](https://codeclimate.com/github/railsconfig/config/badges/issue_count.svg)](https://codeclimate.com/github/railsconfig/config)
-[![Test Coverage](https://codeclimate.com/github/railsconfig/config/badges/coverage.svg)](https://codeclimate.com/github/railsconfig/config/coverage)
+[![Maintainability](https://api.codeclimate.com/v1/badges/85c206c13dce7de090af/maintainability)](https://codeclimate.com/github/railsconfig/config/maintainability)
+[![Test Coverage](https://api.codeclimate.com/v1/badges/85c206c13dce7de090af/test_coverage)](https://codeclimate.com/github/railsconfig/config/test_coverage)
 
 ## Summary
 
 Config helps you easily manage environment specific settings in an easy and usable manner.
 
@@ -270,9 +269,30 @@
 
 ### Merge customization
 
 * `overwrite_arrays` - overwrite arrays found in previously loaded settings file. Default: `true`
 * `knockout_prefix` - ability to remove elements of the array set in earlier loaded settings file. Makes sense only when `overwrite_arrays = false`, otherwise array settings would be overwritten by default. Default: `nil`
+* `merge_nil_values` - `nil` values will overwrite an existing value when merging configs. Default: `true`.
+
+```ruby
+# merge_nil_values is true by default
+c = Config.load_files("./spec/fixtures/development.yml") # => #<Config::Options size=2, ...>
+c.size # => 2
+c.merge!(size: nil) => #<Config::Options size=nil, ...>
+c.size # => nil
+```
+
+```ruby
+# To reject nil values when merging settings:
+Config.setup do |config|
+  config.merge_nil_values = false
+end
+
+c = Config.load_files("./spec/fixtures/development.yml") # => #<Config::Options size=2, ...>
+c.size # => 2
+c.merge!(size: nil) => #<Config::Options size=nil, ...>
+c.size # => 2
+```
 
 Check [Deep Merge](https://github.com/danielsdeleo/deep_merge) for more details.
 
 ### Validation