Problem: Vim incorrectly escapes tags containing "[" in a help buffer
Solution: check if the buffer has the "help" filetype set, instead of
already being a help buffer (Phạm Bình An)
fixes: vim/vim#17224closes: vim/vim#172326af20a9be3
Co-authored-by: Phạm Bình An <phambinhanctb2004@gmail.com>
Co-authored-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>