Documentation/help is missing for regex in the file name field #11435

Hello,

When I was trying to setup a new notification for a new file uploaded using the file name match I found that in most cases entering a valid regex did not work, i.e. every time an error was returned. Currently it is unclear what can be entered in the file name field.
E.g.:

• there is an example: "/^dummy-.+$/i" which works
• none of these work: "/my/folder/.+", "/my/folder/.+"
  Please add some documentation or help with examples.