Nomad changes

docs/snippets/ruby/plugins/stateful_plugin.md

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+```ruby title="Ruby"
+require 'kreuzberg'
+
+class StatefulPlugin
+  def initialize
+    @lock = Mutex.new
+    @count = 0
+  end
+
+  def call(result)
+    @lock.synchronize { @count += 1 }
+    result
+  end
+
+  def count
+    @lock.synchronize { @count }
+  end
+end
+
+plugin = StatefulPlugin.new
+Kreuzberg.register_post_processor('counter', plugin)
+
+config = Kreuzberg::ExtractionConfig.new(
+  postprocessor: { enabled: true }
+)
+
+Kreuzberg.extract_file_sync('document.pdf', config: config)
+puts "Processed: #{plugin.count}"
+```