[DOC] Suppress documentation for internals

Author: nobu

docs/io.rb

@@ -1,8 +1,3 @@
 # The {built-in class for I/O}[https://docs.ruby-lang.org/en/master/IO.html].
 class IO
-  # :stopdoc:
-  module generic_readable
-  end
-  module generic_writable
-  end
 end

ext/stringio/stringio.c

@@ -2244,7 +2244,9 @@ Init_stringio(void)
     rb_define_method(StringIO, "set_encoding_by_bom", strio_set_encoding_by_bom, 0);
 
     {
+	/* :stopdoc: */
 	VALUE mReadable = rb_define_module_under(rb_cIO, "generic_readable");
+	/* :startdoc: */
 	rb_define_method(mReadable, "readchar", strio_readchar, 0);
 	rb_define_method(mReadable, "readbyte", strio_readbyte, 0);
 	rb_define_method(mReadable, "readline", strio_readline, -1);
@@ -2254,7 +2256,9 @@ Init_stringio(void)
 	rb_include_module(StringIO, mReadable);
     }
     {
+	/* :stopdoc: */
 	VALUE mWritable = rb_define_module_under(rb_cIO, "generic_writable");
+	/* :startdoc: */
 	rb_define_method(mWritable, "<<", strio_addstr, 1);
 	rb_define_method(mWritable, "print", strio_print, -1);
 	rb_define_method(mWritable, "printf", strio_printf, -1);