Usage document references deprecated commands

[dkav]

General troubleshooting steps

• [x] I understand that if I ignore these instructions, my issue may be closed without review.
• [X] I have retried my command with --force.
• [X] I ran brew update-reset && brew update and retried my command.
• [X] I ran brew doctor, fixed as many issues as possible and retried my command.
• [X] I have checked the instructions for reporting bugs.
• [x] I made doubly sure this is not a checksum does not match error.

Description of issue

Usage document (USAGE.MD) references commands now depreciated. Commands include brew cask upgrade, brew cask outdated, brew cask list, brew cask doctor, etc.

Command that failed

brew cask upgrade

Output of command with --force --verbose --debug

Warning: Calling brew cask upgrade is deprecated! Use brew upgrade --cask instead.

Output of brew cask doctor

Warning: Calling brew cask doctor is deprecated! Use brew doctor --verbose instead.
==> Homebrew Version
2.4.16-120-g793ab30
==> macOS
10.15.6
==> SIP
Enabled
==> Java
N/A
==> Homebrew Cask Staging Location
/usr/local/Caskroom
==> Homebrew Cask Taps:
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask (3645 casks)
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-versions (161 casks)
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-fonts (1559 casks)
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-drivers (158 casks)
==> $LOAD_PATHS
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/ruby-macho-2.2.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rubocop-rspec-1.43.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rubocop-performance-1.7.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/plist-3.5.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/patchelf-1.3.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/mechanize-2.7.6/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/elftools-1.1.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/bindata-2.4.8/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/activesupport-6.0.3.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/zeitwerk-2.4.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/tzinfo-1.2.7/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/thread_safe-0.3.6/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/i18n-1.8.5/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/concurrent-ruby-1.1.7/lib/concurrent-ruby
/Library/Ruby/Site/2.6.0
/Library/Ruby/Site/2.6.0/universal-darwin19
/Library/Ruby/Site
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/vendor_ruby/2.6.0
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/vendor_ruby/2.6.0/universal-darwin19
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/vendor_ruby
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/universal-darwin19
/usr/local/Homebrew/Library/Homebrew
==> Cask Environment Variables:
BUNDLE_PATH
CHRUBY_VERSION
GEM_HOME
GEM_PATH
HOMEBREW_CASK_OPTS
LC_ALL
PATH
RBENV_VERSION
RUBYLIB
RUBYOPT
RUBYPATH
SHELL

Output of brew tap

{{replace this}}

[vitorgalvao]

Closing in favour of #88680 #88681 #88682.