Update 01_documentation.sql

Add documentation

Author: xylle

examples/official-site/sqlpage/migrations/01_documentation.sql

@@ -251,6 +251,7 @@ INSERT INTO parameter(component, name, description, type, top_level, optional) S
     ('max', 'The maximum value to accept for an input of type number', 'REAL', FALSE, TRUE),
     ('checked', 'Used only for checkboxes and radio buttons. Indicates whether the checkbox should appear as already checked.', 'BOOLEAN', FALSE, TRUE),
     ('multiple', 'Used only for select elements. Indicates that multiple elements can be selected simultaneously. When using multiple, you should add square brackets after the variable name: ''my_variable[]'' as name', 'BOOLEAN', FALSE, TRUE),
+    ('emptyoption', 'Used only for select elements. Add empty option at first', 'BOOLEAN', FALSE, TRUE),
     ('searchable', 'For select and multiple-select elements, displays them with a nice dropdown that allows searching for options.', 'BOOLEAN', FALSE, TRUE),
     ('dropdown', 'An alias for "searchable".', 'BOOLEAN', FALSE, TRUE),
     ('create_new', 'In a multiselect with a dropdown, this option allows the user to enter new values, that are not in the list of options.', 'BOOLEAN', FALSE, TRUE),