Reword "Only 1 allowed" label in security.txt file generator.

[EdOverflow]

The current label is a bit confusing. Maybe we could reword it.

[joker314]

I think it's probably sensible to remove the "Only 1 allowed" tag and also remove the disabled button to "Add another alternative" and treat the Preferred-Languages field as a special case. Alternatively, we could try to make the input box shorter in width and then re-enable the "Add another alternative button" which would handle adding the commas automatically.

[EdOverflow]

Maybe we could create little labels for each language? Something along the lines of this: