Create user command on plugin load.

plugin/init.lua

@@ -0,0 +1,13 @@
+if vim.fn.exists("g:loaded_md-tools") == 0 then
+    local user_cmd = vim.api.nvim_create_user_command
+
+    user_cmd("HeaderPromote", function (opts)
+        require("md-tools").promote()
+    end, {})
+
+    user_cmd("HeaderDemote", function (opts)
+        require("md-tools").demote()
+    end, {})
+
+    vim.api.nvim_set_var("loaded_md-tools", true)
+end