fix ISO reference number of String#=~.

mrblib/string.rb

@@ -135,7 +135,7 @@ class String
   end
 
   ##
-  # ISO 15.2.10.5.5
+  # ISO 15.2.10.5.3
   def =~(re)
     if re.respond_to? :to_str
       raise TypeError, "type mismatch: String given"

test/t/string.rb

@@ -28,6 +28,8 @@ assert('String#==', '15.2.10.5.2') do
   assert_not_equal 'abc', 'cba'
 end
 
+# 'String#=~', '15.2.10.5.3' will be tested in mrbgems.
+
 assert('String#+', '15.2.10.5.4') do
   assert_equal 'ab', 'a' + 'b'
 end
@@ -36,8 +38,6 @@ assert('String#*', '15.2.10.5.5') do
   assert_equal 'aaaaa', 'a' * 5
 end
 
-# 'String#=~', '15.2.10.5.5' will be tested in mrbgems.
-
 assert('String#[]', '15.2.10.5.6') do
   # length of args is 1
   a = 'abc'[0]