Fix a few inconsistencies in the README

[duffuniverse]

Detail

# Ruby 3.4.9

no_method_error = begin
                    1.zeor?
                  rescue NoMethodError => error
                    error
                  end

no_method_error.message
# => "undefined method 'zeor?' for an instance of Integer"

no_method_error.original_message
# => "undefined method 'zeor?' for an instance of Integer"

no_method_error.detailed_message(highlight: false)
# => "undefined method 'zeor?' for an instance of Integer (NoMethodError)\nDid you mean?  zero?"

Exception.method_defined?(:detailed_message)
# => true

https://github.com/ruby/did_you_mean/blob/6740bdcb2844541b46f5244c21adea8386a23607/lib/did_you_mean/core_ext/name_error.rb