Add a few custom plugins and mappings

lua/custom/plugins/lsp-signature.lua

@@ -0,0 +1,10 @@
+-- https://github.com/ray-x/lsp_signature.nvim
+return {
+  'ray-x/lsp_signature.nvim',
+  event = 'VeryLazy',
+  opts = {},
+  config = function(_, opts)
+    require('lsp_signature').setup(opts)
+    vim.keymap.set('i', '<C-g>', vim.lsp.buf.signature_help, { silent = true, noremap = true, desc = 'toggle function signature' })
+  end,
+}