[DOC] Tweaks for String#ord

Author: BurdetteLamar

doc/string/ord.rdoc

@@ -4,3 +4,5 @@ Returns the integer ordinal of the first character of +self+:
   'hello'.ord     # => 104
   'тест'.ord      # => 1090
   'こんにちは'.ord  # => 12371
+
+Related: see {Converting to Non-String}[rdoc-ref:String@Converting+to+Non--5CString].