add support for vimhelp

[printfdebugging]

i use vimhelp for my notes, it's quite nice as one can use the builtin support for ctags to navigate through the notes and interlink them. the only issue is that we don't have images there. it would be great if you could add the support for them too.

[printfdebugging]

@3rd :) has been quite some time, so i thought i should ask if it's possible at all. if it is then i can look into it and create a PR

[printfdebugging]

seems it's possible, i should follow this #163 (html/css impl)