nvim: Set default tabwidth in md, quarto to 2

Makes it easier to read lists, and also easier to work with
markdownlint even if it has not been configured for a given repository
(since its list indentations default to 2 spaces).

nvim/.config/nvim/after/ftplugin/markdown.lua

@@ -1,5 +1,9 @@
 local map = vim.keymap.set
 
+vim.opt.tabstop = 2
+vim.opt.shiftwidth = 2
+vim.opt.softtabstop = 2
+
 if require("core.util").is_available("which-key") then
 	require("which-key").add({
 		{ "<localleader>c", group = "codecells" },

nvim/.config/nvim/after/ftplugin/quarto.lua

@@ -1,5 +1,11 @@
+local map = vim.keymap.set
+
+vim.opt.tabstop = 2
+vim.opt.shiftwidth = 2
+vim.opt.softtabstop = 2
+
 if require("core.util").is_available("quarto") then
-	vim.keymap.set("n", "<localleader>po", require("quarto").quartoPreview, { desc = "show quarto preview" })
+	map("n", "<localleader>po", require("quarto").quartoPreview, { desc = "show quarto preview" })
 end
 
 -- TODO: Puths kernel into local file dir currently,
@@ -65,7 +71,7 @@ end
 vim.api.nvim_create_user_command("JupyterStart", function(opts)
 	startsession(opts)
 end, { nargs = "?" })
-vim.keymap.set("n", "<localleader>cS", ":JupyterStart<cr>", { desc = "start code session", silent = true })
+map("n", "<localleader>cS", ":JupyterStart<cr>", { desc = "start code session", silent = true })
 
 if vim.g.quarto_auto_init_molten_session then
 	vim.api.nvim_create_autocmd({ "BufEnter" }, {