Design new invitation modal

[dromerolovo]

Admins should be able to invite moderators and promote moderators to admin. The Invitation modal should have both options.

The modal should contain the following:

• Title: could be Admin Panel.
• Description paragraph, similar to the one that is implemented, just replace admin for moderator.
• Label 1: Invite a moderator
• Text Field
• Label 2: Promote a moderator
• Text Field
• "Send" Button.

Check Figma for a reference "Invite an admin modal"

[Xazin]

See my comment on #55