Add info about new APIs

samples/calendars_enabled.lua

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+function on_resume()
+    ui:show_text(table.concat(calendar:enabled_calendar_ids(), ", "))
+end

samples/icon-sample.lua

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+-- name = "Icon / private mode sample"
+-- icon = "house"
+-- private_mode = true
+
+function on_resume()
+    ui:show_text("This script have an icon and supports private mode")
+end