[DRE-maint] Bug#990063: ruby2.7: rdoc2.7 man page gives incorrect info about --help-output

[FPacifica]

Package: ruby2.7
Version: 2.7.3-2
Severity: normal

Dear Maintainer,

Trying to generate ruby2.7 html documentation for local use.  The man
page rdoc2.7(1) states:

      Available output formatters: chm, html, ri, xml

       For information on where the output goes, use:
           rdoc --help-output

However when rdoc2.7 --help-output is run it gives the error:

    option --help-output is deprecated: support discontinued

Also the man page is does not explain how to generate html
documentation and the ruby2.7-doc package, unlike other Debian -doc
packages, does not actually provide any documentation in
/usr/share/doc/ruby2.7 other than the changelog and copyright.


-- System Information:
Debian Release: 11.0
  APT prefers testing-security
  APT policy: (500, 'testing-security'), (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.10.0-6-amd64 (SMP w/12 CPU threads)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages ruby2.7 depends on:
ii  libc6                 2.31-12
ii  libruby2.7            2.7.3-2
ii  rubygems-integration  1.18

Versions of packages ruby2.7 recommends:
ii  fonts-lato    2.0-2.1
ii  libjs-jquery  3.5.1+dfsg+~3.5.5-7

ruby2.7 suggests no packages.

-- no debconf information