plugins: add a keymap to display markdown TOC

Co-Authored-by: iGor milhit <igor@milhit.ch>

lua/plugins/markdown/pandoc.lua

@@ -28,6 +28,13 @@ vim.keymap.set('n',
 {desc = 'Toggle autoformat, to deactivate it'}
 )
 
+vim.keymap.set(
+  "n",
+  "<leader>tc",
+  "<cmd>TOC<cr>",
+  { desc = "[vim-pandoc] Display the Table of Content"}
+)
+
 return {
   {
     "vim-pandoc/vim-pandoc",