Custom button and html with [settings api plugin]

You can modify the plugin to add a “Save & Execute” button, but not sure what will you do with that. As the PHP class doesn’t do anything for saving the options, WordPress handles it by default. So it’s tricky that how you’ll implement the execution.

You can add a html type field for documentation.

array(
    'name' => 'docs',
    'label' => __( 'Documentation', 'wpuf' ),
    'type' => 'html',
    'desc' => 'Your docs here'
)