Added hint that you can search users by name, username, or email.

app/views/groups/group_members/_new_group_member.html.haml

@@ -4,7 +4,7 @@
     .col-sm-10
       = users_select_tag(:user_ids, multiple: true, class: 'input-large', scope: :all, email_user: true)
       .help-block
-        Search for existing users or invite new ones using their email address.
+        Search for users by name, username, or email, or invite new ones using their email address.
   .form-group
     = f.label :access_level, "Group Access", class: 'control-label'

app/views/projects/project_members/_new_project_member.html.haml

@@ -4,7 +4,7 @@
     .col-sm-10
       = users_select_tag(:user_ids, multiple: true, class: 'input-large', scope: :all, email_user: true)
       .help-block
-        Search for existing users or invite new ones using their email address.
+        Search for users by name, username, or email, or invite new ones using their email address.
   .form-group
     = f.label :access_level, "Project Access", class: 'control-label'