docs(v3.5.0): update README for integrated mg_dotfiles and security improvements

- Integrated mg_dotfiles as regular directory (not submodule)
- Added .zshrc.local.example template for local configs without secrets
- Added mg_dotfiles/zsh/.zshrc.local to .gitignore to protect API keys
- Updated README to reflect mg_dotfiles integration and new structure
- Added nvim configuration directory with LazyVim setup

mg_dotfiles/nvim/lua/plugins/which-key.lua

@@ -0,0 +1,31 @@
+-- This file contains the configuration for the which-key.nvim plugin in Neovim.
+
+return {
+  -- Plugin: which-key.nvim
+  -- URL: https://github.com/folke/which-key.nvim
+  -- Description: A Neovim plugin that displays a popup with possible keybindings of the command you started typing.
+  "folke/which-key.nvim",
+
+  event = "VeryLazy", -- Load this plugin on the 'VeryLazy' event
+
+  init = function()
+    -- Set the timeout for key sequences
+    vim.o.timeout = true
+    vim.o.timeoutlen = 300 -- Set the timeout length to 300 milliseconds
+  end,
+
+  keys = {
+    {
+      -- Keybinding to show which-key popup
+      "<leader>?",
+      function()
+        require("which-key").show({ global = false }) -- Show the which-key popup for local keybindings
+      end,
+    },
+    {
+      -- Define a group for Obsidian-related commands
+      "<leader>o",
+      group = "Obsidian",
+    },
+  },
+}