filename -> fname
filename -> fname

The rationale for this change is that `makeprgBuild` uses `fname` as the
parameter name to retrieve the file path. Therefore, the documentation
has been changed to match the code.

wezhang/vim-setup,wezhang/vim-setup,wezhang/vim-setup,wezhang/vim-setup,wezhang/vim-setup,wezhang/vim-setup