The documentation site is currently being rewritten. If you can't find what you're looking for please check the github issues and ask for assistance there until the documentation rewrite is complete.
All controls in the WordPress Customizer must belong to a section. If a control is orphan and not assigned to an existing section then it will not be displayed. In the
section argument you will have to use the unique ID of your section.
For info on how to create sections please refer to the sections documentation.Edit this page