Update README.md

README.md

@@ -206,7 +206,7 @@ These two blocks enable or disable specific UI elements.
 
 ![appendRadiobuttonGroup](./Screenshots/appendRadiobuttonGroup.png)
 
-> appends a radio button group element with the given name and label to the UI. If an element with the same name already exists, it is removed before the new one is appended
+> appends a radio button group element (based on an [HTML input elements of type "radio"](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/radio)) with the given name and label to the UI. If an element with the same name already exists, it is removed before the new one is appended. Radiobutton groups are a bit special as they contain a whole group of radio buttons, each with its own label. As a consequence, after appending a new radio button group element, you will have to define a list of radio buttons using the "append Choice" block - and the value of the whole group (i.e., the associated context item) is the index of the currently checked radio button (or `-1` if no button is checked)
 
 ![appendDropDown](./Screenshots/appendDropDown.png)