nvim: Enable linting for fish

nvim/.config/nvim/after/ftplugin/fish.vim

@@ -1 +1,3 @@
 nnoremap <buffer> gq :silent :%!fish_indent %<CR>:w<CR>
+
+autocmd! BufWritePost <buffer> lua require('lint').try_lint()

nvim/.config/nvim/after/plugin/nvim-lint.lua

@@ -4,6 +4,7 @@ vim.keymap.set('n', '<LocalLeader>l', ':lua require(\'lint\').try_lint()<CR>', {
 
 nvim_lint.linters_by_ft = {
   dockerfile = { 'hadolint' },
+  fish       = { 'fish' },
   haskell    = { 'hlint' },
   javascript = { 'eslint' },
   lua        = { 'luacheck' },