In an ArcGIS Online Notebook, when the Files button is selected and the Files pane is active at the default location of /arcgis there is a notice at the bottom of the Files pane indicating "Uploads are not supported in this folder." with a ? icon that is hyperlinked to https://www.esri.com/en-us/arcgis/products/arcgis-online/resources. If this is intended to be a very general link to help then it should be moved outside of this notification box, and likely ought to at least link to what ArcGIS Online Notebook documentation there is at this point. If it is intended to be specific to not uploading files to this folder then it should provide information specific to that issue. This will be in line with context-specific help available in other Esri products, and other applications in general.