docs: update pact.rb comment to reflect core_ext scope

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Saup21

lib/pact.rb

@@ -5,8 +5,9 @@
 
 require 'pact/railtie' if defined?(Rails::Railtie)
 
-# Load blank?/present? polyfill before Zeitwerk eager-loads the rest of the gem.
-# Skipped if active_support (or anything else) has already defined these methods.
+# Load core_ext polyfills (blank?/present?, deep_dup) before Zeitwerk eager-loads
+# the rest of the gem. Each polyfill is skipped if already defined by active_support
+# or any other library loaded by the host application.
 require 'pact/support/core_ext'
 
 module Pact