Update README

README.md

@@ -122,6 +122,32 @@ environment information on the callback request. It is entirely up to
 you how you want to implement the particulars of your application's
 authentication flow.
 
+## Configuring The `origin` Param
+The `origin` url parameter is typically used to inform where a user came from and where, should you choose to use it, they'd want to return to.
+
+There are three possible options:
+
+Default Flow:
+```ruby
+# /auth/twitter/?origin=[URL]
+# No change
+# If blank, `omniauth.origin` is set to HTTP_REFERER
+```
+
+Renaming Origin Param:
+```ruby
+# /auth/twitter/?return_to=[URL]
+# If blank, `omniauth.origin` is set to HTTP_REFERER
+provider :twitter, ENV['KEY'], ENV['SECRET'], origin_param: 'return_to'
+```
+
+Disabling Origin Param:
+```ruby
+# /auth/twitter
+# Origin handled externally, if need be. `omniauth.origin` is not set
+provider :twitter, ENV['KEY'], ENV['SECRET'], origin_param: false
+```
+
 ## Integrating OmniAuth Into Your Rails API
 The following middleware are (by default) included for session management in
 Rails applications. When using OmniAuth with a Rails API, you'll need to add