Open related file of current file.
Use command :OpenRelatedFile<CR>
to open related file. The default map is
between C/C++ header files and source files. You can customize it by adding
a dict g:relatedfile_user_dict
to the .vimrc file. For example:
let g:relatedfile_user_dict = {".md" : [".html"], ".html" : [".md"]}