nvim: Add existing zettel link insertion mappings

Added mapping to insert a link to an existing Zettel with
`<localleader>ni` (note insert), either from normal mode which creates
the complete link, or from visual selection mode which surrounds the
current selection (as visible link text) with the link.

New zettel links still use my own implementation so I have full control
over their naming scheme.

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

@@ -130,6 +130,19 @@ local prose_plugs = {
 				end,
 				desc = "index page",
 			},
+			{
+				"<localleader>ni",
+				function()
+			        require("zk.commands").get("ZkInsertLink")()
+				end,
+				desc = "insert link",
+			},
+			{
+				"<localleader>ni",
+				":'<,'>ZkInsertLinkAtSelection<cr>",
+				mode = "v",
+				desc = "insert link",
+			},
 		},
 	},