Emails: Change text (#18683)

The text was little misunderstanding
A user asked me what password I had choose, but the user shall choose the password them self.

public/app/partials/signup_invited.html

@@ -4,7 +4,7 @@
 	<h3 class="page-sub-heading">Hello {{greeting}}.</h3>
 
 	<div class="modal-tagline p-b-2">
-		<em>{{invitedBy}}</em> has invited you to join Grafana and the organization <span class="highlight-word">{{contextSrv.user.orgName}}</span></br>Please complete the following to accept your invitation and continue:
+		<em>{{invitedBy}}</em> has invited you to join Grafana and the organization <span class="highlight-word">{{contextSrv.user.orgName}}</span></br>Please complete the following and choose a password to accept your invitation and continue:
 	</div>
 
 	<form name="inviteForm" class="login-form gf-form-group">