Wrong documentation on g:jsonnet_fmt_command

[suguruwataru]

In docs, it is said,

vim-jsonnet/doc/vim-jsonnet.txt

Line 73 in b7459b3

let g:jsonnet_fmt_command = "fmt"

However what's actually in the code is:

vim-jsonnet/autoload/jsonnet.vim

Line 10 in b7459b3

let g:jsonnet_fmt_command = "jsonnetfmt"