add rubocop

lua/plugins/lsp.lua

@@ -0,0 +1,14 @@
+return {
+  {
+    "williamboman/mason.nvim",
+    opts = {
+      -- https://github.com/williamboman/mason.nvim?tab=readme-ov-file#introduction
+      -- https://mason-registry.dev/registry/list
+      ensure_installed = {
+        "rubocop",
+        "stylua",
+        "shfmt",
+      },
+    },
+  },
+}