Fix typos and improve code quality

- Fix typo: '3th' → '3rd' in comment
- Fix typo: 'extentions' → 'extensions' (directory renamed)
- Fix method name: 'copy_interface_file' → 'copy_type_file' in TypeGenerator
- Update .rubocop.yml to reference correct directory name
- Update README.md with modern Ruby syntax (Array[] → [])

Author: mike927

.rubocop.yml

@@ -2,6 +2,8 @@ AllCops:
   TargetRubyVersion: 3.2
   NewCops: enable
   SuggestExtensions: false
+  Exclude:
+    - "README.md"
 
 Style/StringLiterals:
   Enabled: true
@@ -21,7 +23,7 @@ Metrics/BlockLength:
 Metrics/MethodLength:
   Exclude:
     - "lib/rspec/json_api/compare_hash.rb"
-    - "lib/extentions/hash.rb"
+    - "lib/extensions/hash.rb"
 
 Metrics/AbcSize:
   Exclude:

README.md

@@ -51,7 +51,7 @@ Generate new type:
 RSpec.describe UsersController, type: :controller do
   describe '#index' do
     let(:expected_schema) do
-      Array[{
+      [{
         id: RSpec::JsonApi::Types::UUID,
         name: String,
         age: Integer,
@@ -204,7 +204,7 @@ let(:expected_schema) do
     id: Integer,
     name: String,
     age: Integer,
-    notes: Array[String]
+    notes: [String]
   }
 end
 ```
@@ -231,7 +231,7 @@ end
 ### Interface match
 ```ruby
 let(:expected_schema) do
-    Array[RSpec::JsonApi::Interfaces::PERSON]
+    [RSpec::JsonApi::Interfaces::PERSON]
 end
 ```
 

lib/extentions/array.rb lib/extensions/array.rblib/extentions/array.rb renamed to lib/extensions/array.rb

@@ -6,7 +6,7 @@ module Generators
       class TypeGenerator < Rails::Generators::NamedBase
         source_root File.expand_path("templates", __dir__)
 
-        def copy_interface_file
+        def copy_type_file
           create_file "spec/rspec/json_api/types/#{file_name}.rb", <<~FILE
             module RSpec
               module JsonApi

lib/extentions/hash.rb lib/extensions/hash.rblib/extentions/hash.rb renamed to lib/extensions/hash.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-# Load 3th party libraries
+# Load 3rd party libraries
 require "json"
 require "diffy"
 require "active_support/core_ext/object/blank"
@@ -10,9 +10,9 @@
 require "rspec/json_api/compare_hash"
 require "rspec/json_api/compare_array"
 
-# Load extentions
-require "extentions/hash"
-require "extentions/array"
+# Load extensions
+require "extensions/hash"
+require "extensions/array"
 
 # Load matchers
 require "rspec/json_api/matchers"