[doc] RadioButtonWidget (#9733)

frontend/ui/widget/radiobuttontable.lua

@@ -1,3 +1,7 @@
+--[[--
+A button table to be used in dialogs and widgets.
+]]
+
 local Blitbuffer = require("ffi/blitbuffer")
 local CheckButton = require("ui/widget/checkbutton")
 local Device = require("device")

frontend/ui/widget/radiobuttonwidget.lua

@@ -1,3 +1,34 @@
+--[[--
+Widget that allows selecting an entry from a @{ui.widget.radiobuttontable|RadioButton} list.
+
+
+Example:
+    local RadioButtonWidget = require("ui/widget/radiobuttonwidget")
+
+    local radio_buttons = {
+        { {text = _("Radio 1"), provider = 1} },
+        { {text = _("Radio 2"), provider = 2, checked = true} },
+        { {text = _("Radio 3"), provider = "identifier"} },
+    }
+    UIManager:show(RadioButtonWidget:new{
+        title_text = _("Example Title"),
+        info_text = _("Some more information"),
+        cancel_text = _("Close"),
+        ok_text = _("Apply"),
+        width_factor = 0.9,
+        radio_buttons = radio_buttons,
+        callback = function(radio)
+            if radio.provider == 1 then
+                -- do something here
+            elseif radio.provider == 2 then
+                -- do some other things here
+            elseif radio.provider == "identifier" then
+                -- or do a third thing here
+            end
+        end,
+    })
+]]
+
 local Blitbuffer = require("ffi/blitbuffer")
 local ButtonTable = require("ui/widget/buttontable")
 local CenterContainer = require("ui/widget/container/centercontainer")