feat: add some markdown related plugins.

lua/plugins/markdown.lua

@@ -0,0 +1,13 @@
+vim.pack.add({
+  { src = "https://github.com/tadmccorkle/markdown.nvim" },
+  { src = "https://github.com/MeanderingProgrammer/render-markdown.nvim" },
+  { src = "https://github.com/Kicamon/markdown-table-mode.nvim" },
+})
+
+require("render-markdown").setup({
+  completions = { lsp = { enabled = true, } },
+})
+
+require("markdown").setup()
+
+require("markdown-table-mode").setup()