Fix incorrect mutator comments

I used a script which detects duplicate comments:

    require 'parser/current'
    require 'pathname'

    require 'concord'

    class Comment
      include Equalizer.new(:text)

      def initialize(path, comment)
        @path    = path
        @comment = comment
      end

      def text
        comment.text
      end

      def <=>(other)
        text <=> other.text
      end

      attr_reader :path, :comment
    end

    comments =
      Pathname
        .glob('lib/**/*.rb')
        .flat_map do |path|
          Parser::CurrentRuby
            .parse_with_comments(path.read)
            .last
            .map do |comment|
              Comment.new(path, comment)
            end
        end

    @seen = Set.new

    ignores = [
      '#',
      '#   otherwise',
      /\A# [A-Z]\w+\z/,
      /\A# rubocop:disable \w+/,
      /\A# @\w/,
      /\A# @\w/,
      /\A# @\w/,
      /\A# @\w/,
    ]

    duplicates = []

    comments
      .reject do |comment|
        ignores.any? { |ignore| ignore === comment.text }
      end
      .sort
      .group_by { |comment| comment.text }
      .reject { |_, comments| comments.one? }
      .sort_by { |_, comments| comments.size }
      .each do |text, comments|
        next if comments.one?
        warn text

        comments.each do |comment|
          warn "  #{comment.path}:#{comment.comment.loc.line}"
        end
      end

lib/mutant/mutator/node/and_asgn.rb

@@ -2,7 +2,7 @@ module Mutant
   class Mutator
     class Node
 
-      # OpAsgn mutator
+      # AndAsgn mutator
       class AndAsgn < self
 
         handle(:and_asgn)

lib/mutant/mutator/node/defined.rb

@@ -1,7 +1,7 @@
 module Mutant
   class Mutator
     class Node
-      # Namespace for define mutations
+      # Namespace for `defined?` mutations
       class Defined < self
 
         handle(:defined?)

lib/mutant/mutator/node/or_asgn.rb

@@ -2,7 +2,7 @@ module Mutant
   class Mutator
     class Node
 
-      # OpAsgn mutator
+      # OrAsgn mutator
       class OrAsgn < self
 
         handle(:or_asgn)