nvim: Disable line length diagnostic for md files

By default disable the line length for any markdown file. I never use it
and I always turn it off. If I need it for a specific project I can
still figure out how to make the configuration override this.

nvim/.config/nvim/lua/plugins/linting.lua

@@ -22,6 +22,7 @@ return {
 				"mfussenegger/nvim-lint",
 				config = function()
 					require("lint").linters_by_ft = linters
+					require("lint").linters.markdownlint.args = { "--stdin", "--disable", "MD013", "--" }
 					vim.api.nvim_create_autocmd({ "BufWritePost", "InsertLeave" }, {
 						callback = function()
 							if not vim.g.disable_autolint then