feat: add fish support

lua/custom/plugins/fish.lua

@@ -0,0 +1,12 @@
+return {
+  'dag/vim-fish',
+  ft = 'fish',
+  config = function()
+    vim.bo.filetype = 'fish'
+    vim.cmd 'compiler fish'
+    vim.bo.textwidth = 79
+    -- vim.bo.foldmethod = 'expr'
+    -- vim.bo.foldexpr = 'nvim_treesitter#foldexpr()'
+    -- vim.cmd 'setlocal foldlevelstart=1'
+  end,
+}