Each section has an ID which is hard coded into the files. They identify each section.
You can change the ID of the sections directly within the files.
In your Admin Dashboard navigate to Appearance > Editor and open the /sections folder.
Locate the section file you wish to edit.
At the top of the file you will see something like this (example):
section id="features" class="features"
Change the ID name to whatever you wish. Then you will be able to use that ID in your menu.