Manual environment setup for docs site is incorrect

[fdmarcin]

When I followed the instructions at https://developers.home-assistant.io/docs/documenting#manual-environment on Fedora 43, I get this error (tested on up to date current on 2026-03-12):

$ bundle install
Bundle complete! 15 Gemfile dependencies, 68 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
1 installed gem you directly depend on is looking for funding.
  Run `bundle fund` for details

$ ruby -v
ruby 3.4.8 (2025-12-17 revision 995b59f666) +PRISM [x86_64-linux]

$ bundle exec rake generate
/home/marcin/.local/share/gem/ruby/gems/stringex-2.8.6/lib/stringex.rb:3: warning: ostruct was loaded from the standard library, but will no longer be part of the default gems starting from Ruby 4.0.0.
You can add ostruct to your Gemfile or gemspec to silence this warning.
## Generating Site with Jekyll
Generating CSS failed

$ bundle exec rake preview
/home/marcin/.local/share/gem/ruby/gems/stringex-2.8.6/lib/stringex.rb:3: warning: ostruct was loaded from the standard library, but will no longer be part of the default gems starting from Ruby 4.0.0.
You can add ostruct to your Gemfile or gemspec to silence this warning.
Starting to watch source with Jekyll and Sass.
Now listening on http://localhost:4000
/home/marcin/.local/share/gem/ruby/gems/stringex-2.8.6/lib/stringex.rb:3: warning: ostruct was loaded from the standard library, but will no longer be part of the default gems starting from Ruby 4.0.0.
You can add ostruct to your Gemfile or gemspec to silence this warning.
/home/marcin/.local/share/gem/ruby/gems/stringex-2.8.6/lib/stringex.rb:3: warning: ostruct was loaded from the standard library, but will no longer be part of the default gems starting from Ruby 4.0.0.
You can add ostruct to your Gemfile or gemspec to silence this warning.
/home/marcin/.local/share/gem/ruby/gems/stringex-2.8.6/lib/stringex.rb:3: warning: ostruct was loaded from the standard library, but will no longer be part of the default gems starting from Ruby 4.0.0.
You can add ostruct to your Gemfile or gemspec to silence this warning.
/home/marcin/.local/share/gem/ruby/gems/stringex-2.8.6/lib/stringex.rb:3: warning: ostruct was loaded from the standard library, but will no longer be part of the default gems starting from Ruby 4.0.0.
You can add ostruct to your Gemfile or gemspec to silence this warning.
/home/marcin/.local/share/gem/ruby/gems/stringex-2.8.6/lib/stringex.rb:3: warning: ostruct was loaded from the standard library, but will no longer be part of the default gems starting from Ruby 4.0.0.
You can add ostruct to your Gemfile or gemspec to silence this warning.
rake aborted!
Errno::ENOENT: No such file or directory - jekyll (Errno::ENOENT)
/home/marcin/dev/ha/home-assistant.io/Rakefile:86:in 'Process.spawn'
/home/marcin/dev/ha/home-assistant.io/Rakefile:86:in 'block in <top (required)>'
/home/marcin/.local/share/gem/ruby/gems/rake-13.3.1/exe/rake:27:in '<top (required)>'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/cli/exec.rb:58:in 'Kernel.load'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/cli/exec.rb:58:in 'Bundler::CLI::Exec#kernel_load'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/cli/exec.rb:23:in 'Bundler::CLI::Exec#run'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/cli.rb:451:in 'Bundler::CLI#exec'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/vendor/thor/lib/thor/command.rb:28:in 'Bundler::Thor::Command#run'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in 'Bundler::Thor::Invocation#invoke_command'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/vendor/thor/lib/thor.rb:527:in 'Bundler::Thor.dispatch'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/cli.rb:34:in 'Bundler::CLI.dispatch'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/vendor/thor/lib/thor/base.rb:584:in 'Bundler::Thor::Base::ClassMethods#start'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/cli.rb:28:in 'Bundler::CLI.start'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/exe/bundle:28:in 'block in <top (required)>'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/lib/bundler/friendly_errors.rb:117:in 'Bundler.with_friendly_errors'
/home/marcin/.local/share/gem/ruby/gems/bundler-2.5.3/exe/bundle:20:in '<top (required)>'
/usr/bin/bundle:25:in 'Kernel#load'
/usr/bin/bundle:25:in '<main>'
Tasks: TOP => preview
(See full trace by running task with --trace)