Fix more links in another assignments view

Cf. 74aadbb6

app/views/assignments/index.html.erb

@@ -9,7 +9,7 @@
             <% assignments_on_date.each do |assignment| %>
               <li class="<%= assignment.session.starts_at < now ? "past" : "future" %>">
                 <span class="tabular-nums"><%= assignment.session.starts_at.strftime('%H:%M') %> &ndash; <%= assignment.session.ends_at.strftime('%H:%M') %></span>:
-                <%= link_to assignment.session.title, assignment.session %> @ <%= assignment.session.stage.name %>
+                <%= link_to assignment.session.title, conference_session_path(assignment.session.conference, assignment.session) %> @ <%= assignment.session.stage.name %>
                 <small><% assignment.session.assignments.map(&:user).each do |other_user| %>
                   <%= render partial: 'application/user_avatar', locals: { user: other_user } %>
                 <% end %></small>