bitwise vs. logical operators for boolean arithmetic

| and || both work for boolean arithmetic, e.g. in

some_flag = false
some_array.each do |element|
    some_flag ||= do_something(element)
end

||= could be interchanged with |=. Similarly with & and &&. However, traditionally the single character operators | and & are used for bitwise arithmetic, whereas the double character operators || and && are used for boolean arithmetic. I can't think of a good reason for breaking from this tradition, whereas adhering to tradition follows the Principle of Least Surprise, therefore I'm considering submitting a pull request to add this guideline. However I'd welcome other opinions before I do so.

Start with issue #300 and review its six comments to understand whether consensus exists on a boolean-operator guideline. The issue body is the only entry point mentioned; done would require an agreed guideline and a clear decision recorded in the style guide.