Fix ToRdoc#accept_table

[tompng]

Document of Integer#ceil in ruby 3.4.0dev have table. RDoc fails to show tables in text format.

Fix ri Integer#ceil

# ruby -v
ruby 3.4.0dev (2024-09-27T17:45:22Z master 027ef60500) +PRISM [x86_64-linux]
# ri Integer#ceil
/opt/ruby/lib/ruby/3.4.0+0/rdoc/markup/to_rdoc.rb:265:in 'Array#zip': wrong argument type NilClass (must respond to :each) (TypeError)

    @res << header.zip(widths, aligns) do |h, w, a|

Fix IRB crash

irb(main):001> 1.[TAB][TAB]
/opt/ruby/lib/ruby/3.4.0+0/rdoc/markup/to_rdoc.rb:265:in 'Array#zip': wrong argument type NilClass (must respond to :each) (TypeError)

[colby-swandale]

Could we separate the various fixes into their own commits, it would make reviewing each fix much easier

[tompng]

Could we separate the various fixes into their own commits

I removed The change to lib/rdoc/markup/to_tt_only.rb that adds alias accept_table do_nothing.
Now this pull request only contain one fix: ToRdoc#accept_table. This single fix will solve both ri Integer#ceil crash and irb completion crash which is the same cause.

[st0012]

Thank you 👍