nvim: after/plugin/nvim-lint: Enable actionlint

Run actionlint on save for GitHub Action workflow yaml files.

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

@@ -16,3 +16,12 @@ nvim_lint.linters_by_ft = {
   typescript = { 'eslint_d' },
   yaml       = { 'yamllint' },
 }
+
+vim.api.nvim_create_autocmd({ "BufWritePost" }, {
+  pattern  = "*/.github/workflows/*.y{a,}ml",
+  callback = function()
+    local linter = require('lint').linters.actionlint
+    linter.name  = 'actionlint'
+    require("lint").lint(linter)
+  end,
+})