Rakefile in ruby_parser-3.8.3 vs Rakefile in ruby_parser-3.8.4

@@ -6,9 +6,10 @@
 require "hoe"
 
 Hoe.plugin :seattlerb
 Hoe.plugin :racc
 Hoe.plugin :isolate
+Hoe.plugin :rdoc
 
 Hoe.add_include_dirs "../../sexp_processor/dev/lib"
 Hoe.add_include_dirs "../../minitest/dev/lib"
 Hoe.add_include_dirs "../../oedipus_lex/dev/lib"