README.md in configurations-1.4.0 vs README.md in configurations-2.0.0.pre

@@ -8,11 +8,11 @@
 
 `gem install configurations`
 
 or with Bundler
 
-`gem 'configurations', '~> 1.4.0'`
+`gem 'configurations', '~> 2.0.0.pre'`
 
 Configurations uses [Semver 2.0](http://semver.org/)
 
 ## Compatibility
 
@@ -53,10 +53,27 @@
 ```
 MyGem.configuration.class #=> 'oooh wow'
 MyGem.configuration.foo.bar.baz #=> 'fizz'
 ```
 
+Undefined properties on an arbitrary configuration will return `nil`
+
+```
+MyGem.configuration.not_set #=> nil
+```
+
+If you want to define the behaviour for not set properties yourself, use `not_configured`.
+
+```
+module MyGem
+  not_configured do |prop|
+	raise NoMethodError, "#{prop} must be configured"
+  end
+end
+```
+
+
 ### Second way: Restricted Configuration
 
 If you just want some properties to be configurable, consider this option
 
 ```
@@ -85,10 +102,26 @@
 ```
 MyGem.configuration.foo #=> 'FOO'
 MyGem.configuration.bar.baz #=> 'FIZZ'
 ```
 
+Not configured properties on a restricted configuration will raise `NoMethodError`
+
+```
+MyGem.configuration.not_set #=> <#NoMethodError>
+```
+
+If you want to define the behaviour for not set properties yourself, use `not_configured`. This will only affect properties set to configurable. All not configurable properties will raise `NoMethodError`.
+
+```
+module MyGem
+  not_configured do |prop|
+	warn :not_configured, "Please configure #{prop} or live in danger"
+  end
+end
+```
+
 ### Third way: Type Restricted Configuration
 
 If you want to make sure your configurations only accept one type, consider this option
 
 ```
@@ -119,22 +152,22 @@
 ```
 module MyGem
   include Configurations
   configurable :foo do |value|
 
-    # The return value is what gets assigned, unless it is nil,
-    # in which case the original value persists
-    #
-    value + ' ooooh my'
+	# The return value is what gets assigned, unless it is nil,
+	# in which case the original value persists
+	#
+	value + ' ooooh my'
   end
   configurable String, bar: :baz do |value|
 
-    # value is guaranteed to be a string at this point
-    #
-    unless %w(bi ba bu).include?(value)
-      raise ArgumentError, 'baz needs to be one of bi, ba, bu'
-    end
+	# value is guaranteed to be a string at this point
+	#
+	unless %w(bi ba bu).include?(value)
+	  raise ArgumentError, 'baz needs to be one of bi, ba, bu'
+	end
   end
 end
 ```
 
 Gives your users:
@@ -164,11 +197,11 @@
 ```
 module MyGem
   include Configurations
   configurable :foo, :bar
   configuration_method :foobar do |arg|
-    foo + bar + arg
+	foo + bar + arg
   end
 end
 ```
 
 Your users do:
@@ -191,10 +224,10 @@
 
 ```
 module MyGem
   include Configurations
   configuration_defaults do |c|
-    c.foo.bar.baz = 'BAR'
+	c.foo.bar.baz = 'BAR'
   end
 end
 ```
 
 ### Get a hash if you need it