Fix minor typos

```
codespell **/*.rb **/*.md -L initalize,unvalid
```

spec/authorization_spec.rb

@@ -169,7 +169,7 @@ def to_params(*args, **kwargs, &block)
       expect(controller.policy_scope(Post)).to eq :published
     end
 
-    it "allows policy scope class to be overriden" do
+    it "allows policy scope class to be overridden" do
       expect(controller.policy_scope(Post, policy_scope_class: PublicationPolicy::Scope)).to eq :published
     end
 

spec/spec_helper.rb

@@ -313,7 +313,7 @@ def self.all; end
 class ThreadPolicy < BasePolicy
   class Scope < BaseScope
     def resolve
-      # deliberate wrong useage of the method
+      # deliberate wrong usage of the method
       scope.all(:unvalid, :parameters)
     end
   end