Fix links to the page directory files

https://bugs.ruby-lang.org/issues/18468

Author: nobu

doc/optparse/creates_option.rdoc

@@ -1,7 +1,7 @@
 Creates an option from the given parameters +params+.
-See {Parameters for New Options}[./doc/optparse/option_params_rdoc.html].
+See {Parameters for New Options}[./option_params.rdoc].
 
 The block, if given, is the handler for the created option.
 When the option is encountered during command-line parsing,
 the block is called with the argument given for the option, if any.
-See {Option Handlers}[./option_params_rdoc.html#label-Option+Handlers].
+See {Option Handlers}[./option_params.rdoc#label-Option+Handlers].

doc/optparse/option_params.rdoc

@@ -410,7 +410,7 @@ from the default \String to an instance of another class.
 There are a number of built-in converters.
 You can also define custom converters.
 
-See {Argument Converters}[./argument_converters_rdoc.html].
+See {Argument Converters}[./argument_converters.rdoc].
 
 === Descriptions
 

doc/optparse/tutorial.rdoc

@@ -541,7 +541,7 @@ Executions:
   [#<Date: 2001-02-03 ((2451944j,0s,0n),+0s,2299161j)>, Date]
 
 You can also define custom converters.
-See {Argument Converters}[./argument_converters_rdoc.html]
+See {Argument Converters}[./argument_converters.rdoc]
 for both built-in and custom converters.
 
 === Help
@@ -657,7 +657,7 @@ Though you may never need to call it directly,
 here's the core method for defining an option:
 
 - \Method \OptionParser#make_switch accepts an array of parameters and a block.
-  See {Parameters for New Options}[./option_params_rdoc.html].
+  See {Parameters for New Options}[./option_params.rdoc].
   This method is unlike others here in that it:
   - Accepts an <em>array of parameters</em>;
     others accept a <em>sequence of parameter arguments</em>.

lib/optparse.rb

@@ -50,7 +50,7 @@
 #
 # === New to \OptionParser?
 #
-# See the {Tutorial}[./doc/optparse/tutorial_rdoc.html].
+# See the {Tutorial}[optparse/tutorial.rdoc].
 #
 # === Introduction
 #
@@ -420,7 +420,7 @@
 # === Further documentation
 #
 # The above examples, along with the accompanying
-# {Tutorial}[./doc/optparse/tutorial_rdoc.html],
+# {Tutorial}[optparse/tutorial.rdoc],
 # should be enough to learn how to use this class.
 # If you have any questions, file a ticket at http://bugs.ruby-lang.org.
 #