Invitations page: Clarify process of code/link generation

[sushidave]

trafficstars

Describe the bug After generating an invitation code/link there appears to be no option to create more codes/links. The displayed text doesn't make it clear if just one or several codes/links may be generated per user.

To Reproduce Steps to reproduce the behavior:

1. Go to the 'invitation page'
2. Click on the button to generate a code/link.
3. Copy the link.
4. Dead end.

Expected behavior Add the possibility to generate more codes/links or declare in the intro text that only one code/link may be generated per user.

[appinteractive]

We could also add a counter like 1/1 or 1 of 1