[ruby/logger] Mention behavior when logdev is a nil in the document
https://github.com/ruby/logger/commit/8dc270ee23
Added by pocke (Masataka Kuwabara) about 5 years ago
[ruby/logger] Mention behavior when logdev is a nil in the document
https://github.com/ruby/logger/commit/8dc270ee23