feat: added markdown.nvim for a better experience when editing .md files

lua/plugins/markdown.lua

+return {
+    'MeanderingProgrammer/markdown.nvim',
+    main = "render-markdown",
+    opts = {},
+    name = 'render-markdown',                                                            -- Only needed if you have another plugin named markdown.nvim
+    dependencies = { 'nvim-treesitter/nvim-treesitter', 'nvim-tree/nvim-web-devicons' }, -- if you prefer nvim-web-devicons
+}