key → private_key

Updates the default params to use the new `private_key` param.
Updates the README to document the new method for obtaining a key.

Author: mattantonelli

README.md

@@ -22,7 +22,7 @@ Full documentation for this library can be found [here](https://xivapi.github.io
 
 ## Usage
 
-Start by initializing a client. You can obtain an API key by creating a new XIVAPI application [here](https://www.xivapi.com/app).
+Start by initializing a client. You can obtain an API key by signing in to XIVAPI [here](https://www.xivapi.com/app). The key is available under the Dev Account page after signing in.
 
 ```rb
 require 'xivapi'

lib/xivapi.rb

@@ -67,7 +67,7 @@ def poll_rate=(rate)
 
     # @return [Hash] The default parameters for the client
     def default_params
-      { key: @api_key, language: @language }
+      { private_key: @api_key, language: @language }
     end
   end
 end