Re-translate the Japanese version (#1871)

* Retranslate Japanese docs with GPT-5.4

* Retranslate Japanese code with GPT-5.4

ja/codes/ruby/chapter_hashing/simple_hash.rb

@@ -0,0 +1,62 @@
+=begin
+File: simple_hash.rb
+Created Time: 2024-04-14
+Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
+=end
+
+### 加算ハッシュ ###
+def add_hash(key)
+  hash = 0
+  modulus = 1_000_000_007
+
+  key.each_char { |c| hash += c.ord }
+
+  hash % modulus
+end
+
+### 乗算ハッシュ ###
+def mul_hash(key)
+  hash = 0
+  modulus = 1_000_000_007
+
+  key.each_char { |c| hash = 31 * hash + c.ord }
+
+  hash % modulus
+end
+
+### XOR ハッシュ ###
+def xor_hash(key)
+  hash = 0
+  modulus = 1_000_000_007
+
+  key.each_char { |c| hash ^= c.ord }
+
+  hash % modulus
+end
+
+### 回転ハッシュ ###
+def rot_hash(key)
+  hash = 0
+  modulus = 1_000_000_007
+
+  key.each_char { |c| hash = (hash << 4) ^ (hash >> 28) ^ c.ord }
+
+  hash % modulus
+end
+
+### Driver Code ###
+if __FILE__ == $0
+  key = "Hello アルゴリズム"
+
+  hash = add_hash(key)
+  puts "加算ハッシュ値は #{hash}"
+
+  hash = mul_hash(key)
+  puts "乗算ハッシュ値は #{hash}"
+
+  hash = xor_hash(key)
+  puts "XORハッシュ値は #{hash}"
+
+  hash = rot_hash(key)
+  puts "ローテーションハッシュ値は #{hash}"
+end