nvim: Enter notes dir when calling zettel index

When switching the current buffer to the Zettelkasten index page
(`<leader>ni`), we now also switch the working directory to the
corresponding notes directory.

nvim/.config/nvim/lua/plugins/prose.lua

@@ -103,6 +103,9 @@ local prose_plugs = {
 	-- simple static markdown linking and link following using zettel IDs
 	{
 		"marty-oehme/zettelkasten.nvim",
+		dependencies = {
+			"mickael-menu/zk-nvim", -- for the CD when opening index
+		},
 		ft = writing_ft,
 		keys = {
 			{
@@ -122,6 +125,7 @@ local prose_plugs = {
 			{
 				"<leader>ni",
 				function()
+			        require("zk.commands").get("ZkCd")()
 					require("zettelkasten").index_open()
 				end,
 				desc = "index page",