Enhancement-request: Please add ability to generate HTML for vim plugin vimdoc help files found under LOCAL ADDITIONS

[bdutta]

Please add ability to generate HTML for vim plugin vimdoc help files found under LOCAL ADDITIONS. Many vim plugins have their own vimhelp txt files, s.a. for airline, NERDtree, vim-go etc. Would be very nice to be able to generate HTML form documentation for such help files as well.