add markdown plugin

lua/plugins/markdown.lua

@@ -0,0 +1,20 @@
+return {
+  'MeanderingProgrammer/render-markdown.nvim',
+  dependencies = { 'nvim-treesitter/nvim-treesitter', 'echasnovski/mini.nvim' }, -- if you use the mini.nvim suite
+  -- dependencies = { 'nvim-treesitter/nvim-treesitter', 'echasnovski/mini.icons' }, -- if you use standalone mini plugins
+  -- dependencies = { 'nvim-treesitter/nvim-treesitter', 'nvim-tree/nvim-web-devicons' }, -- if you prefer nvim-web-devicons
+  ---@module 'render-markdown'
+  ---@type render.md.UserConfig
+  opts = {},
+  init = function()
+    vim.api.nvim_create_autocmd('FileType', {
+      group = vim.api.nvim_create_augroup('markdown.fold', {}),
+      pattern = 'markdown',
+      callback = function()
+        -- sets local folding options for markdown
+        vim.opt_local.foldmethod = 'expr'
+        vim.opt_local.foldexpr = 'v:lua.vim.treesitter.foldexpr()'
+      end,
+    })
+  end,
+}