fix: Update mappings README

Author: zenbro

README.md

@@ -165,20 +165,20 @@ can be used by creating key mappings:
 
 ```lua
 -- Delete the mark under the cursor
-vim.keymap.set("m;", require("guttermarks.actions").delete_mark)
+vim.keymap.set("n", "m;", require("guttermarks.actions").delete_mark)
 
 -- Navigate to next/previous mark in current buffer
-vim.keymap.set("]m", require("guttermarks.actions").next_buf_mark)
-vim.keymap.set("[m", require("guttermarks.actions").prev_buf_mark)
+vim.keymap.set("n", "]m", require("guttermarks.actions").next_buf_mark)
+vim.keymap.set("n", "[m", require("guttermarks.actions").prev_buf_mark)
 
 -- Send marks to quickfix (and open it)
-vim.keymap.set("<leader>mq", function()
+vim.keymap.set("n", "<leader>mq", function()
     require("guttermarks.actions").marks_to_quickfix()
     vim.cmd("copen")
 end)
 
 -- Send marks to quickfix (include special marks)
-vim.keymap.set("<leader>mQ", function()
+vim.keymap.set("n", "<leader>mQ", function()
     require("guttermarks.actions").marks_to_quickfix({
         special_mark = true,
     })