Add vim-plug plugin manager function.

nvim/init.vim

@@ -3,8 +3,25 @@
 " Copyright 2022-2023 Inference
 " SPDX-License-Identifier: BSD 3-Clause-Clear
 
-" Version: 0.0.2.2
+" Version: 0.1.0.3
 
 
+" Editor.
 set number
 set tabstop=4
+
+" Plugins.
+call plug#begin()
+" The default plugin directory will be as follows:
+"   - Vim (Linux/macOS): '~/.vim/plugged'
+"   - Vim (Windows): '~/vimfiles/plugged'
+"   - Neovim (Linux/macOS/Windows): stdpath('data') . '/plugged'
+" You can specify a custom plugin directory by passing it as the argument
+"   - e.g. `call plug#begin('~/.vim/plugged')`
+"   - Avoid using standard Vim directory names like 'plugin'
+
+Plug 'nvim-tree/nvim-tree.lua'
+
+" Initialize plugin system
+" - Automatically executes `filetype plugin indent on` and `syntax enable`.
+call plug#end()