Add markdown linting commands and update keymaps

- Introduced commands to enable/disable automatic markdown linting.
- Updated keymaps to reflect changes in markdown linting behavior.

lua/autocmds.lua

@@ -52,7 +52,7 @@ vim.api.nvim_create_autocmd("FileType", {
 	end,
 })
 
--- Markdown: Prettier defaults (2 spaces)
+-- Markdown: Prettier defaults (2 spaces) + spellcheck
 vim.api.nvim_create_autocmd("FileType", {
 	group = aug,
 	pattern = "markdown",
@@ -61,6 +61,7 @@ vim.api.nvim_create_autocmd("FileType", {
 		vim.opt_local.tabstop = 2 -- Display as 2 spaces
 		vim.opt_local.shiftwidth = 2 -- Indent by 2
 		vim.opt_local.softtabstop = 2
+		vim.opt_local.spell = true -- Enable spellcheck for markdown
 	end,
 })