Remove Lodestone endpoint

This endpoint has been removed from the API, so remove it from the
library as well.

README.md

@@ -124,14 +124,6 @@ See the examples below to get a better idea of how to access the data.
 => "!Kill_For_A_Friend!"
 ```
 
-#### Lodestone
-```rb
->> updates = client.lodestone(:updates)
-=> ...
->> updates.first.title
-=> "Companion App Updated (Sep. 18)"
-```
-
 #### Patch List
 ```rb
 >> patch = client.patch_list.last

lib/xivapi/request.rb

@@ -139,13 +139,6 @@ def pvp_team_search(name: nil, server: nil, columns: [])
     XIVAPI::Paginator.new(self, params, 'pvpteam/search', LODESTONE_LIMIT)
   end
 
-  # @param category [String, Symbol] Category to retrieve (e.g. News, Updates, DevBlog)
-  # @return [Array<OpenStruct>] The requested Lodestone data
-  def lodestone(category)
-    endpoint = category.to_s.downcase.delete('_')
-    request(self, "lodestone/#{endpoint}")
-  end
-
   # @return [Array<OpenStruct>] List of game patches
   def patch_list
     request(self, 'patchlist')