updated Getting Started with docu on new aliased sequence functionality

GETTING_STARTED.md

@@ -401,6 +401,35 @@ factory :post do
 end
 ```
 
+Sequences can also have aliases. The sequence aliases share the same counter:
+
+```ruby
+factory :user do
+  sequence(:email, 1000, :aliases => [:sender, :receiver]) {|n| "person#{n}@example.com" }
+end
+
+# will increase value counter for :email which is shared by :sender and :receiver
+FactoryGirl.next(:sender) 
+```
+
+Define aliases and use default value (=1) for the counter
+
+```ruby
+factory :user do
+  sequence(:email, :aliases => [:sender, :receiver]) {|n| "person#{n}@example.com" }
+end
+```
+
+Setting the value using the :value option:
+
+```ruby
+factory :user do
+  sequence(:email, :value => 'b', :aliases => [:sender, :receiver]) {|n| "person#{n}@example.com" }
+end
+```
+
+The value just needs to support the `#next` method. Here the next value will be 'b'.
+
 Traits
 ------