[docgen] Update doc/orgmode.txt

skip-checks: true

Author: github-actions

doc/orgmode.txt

@@ -400,7 +400,7 @@ For example, lets add option to export to `rtf` format via `pandoc`:
         f = {
           label = 'Export to RTF format',
           action = function(exporter)
-            local current_file = vim.fn.bufname()
+            local current_file = vim.api.nvim_buf_get_name(0)
             local target = vim.fn.fnamemodify(current_file, ':p:r')..'.rtf'
             local command = {'pandoc', current_file, '-o', target}
             local on_success = function(output)