Revise "No Braces Options Hash" rule

https://github.com/rubocop-hq/ruby-style-guide#no-braces-opts-hash

See also https://github.com/rubocop-hq/rubocop/issues/7641

foo(kw: 1) and foo({kw: 1}) will have different meanings in Ruby 3. And Ruby warns them since Ruby 2.7 if it is used unexpectedly, and Ruby raises an argument error in Ruby 3.
But the style guide says "always omit the curly braces".

So I propose revising the guide.
I think the guide should mention both cases, Hash and keyword arguments.

For example:

def foo(a:, b:)
  p a, b
end

def bar(hash)
  p hash
end

# good
foo a: 1, b: 2
# good
bar({a: 1, b: 2})


# bad - foo expects keyword arguments, but it passes a Hash
foo({a: 1, b: 2})
# bad - bar expects a hash, but it passes keyword arguments
bar a: 1, b: 2

Start with the linked “No Braces Options Hash” section in the Ruby Style Guide and review the related RuboCop issue 7641. Revise the guidance and examples to distinguish hashes from keyword arguments under Ruby 2.7 and Ruby 3; done when both cases and their intended forms are documented.