Add link to documentation

Fixes INFRA-224

app/settings.py

@@ -62,3 +62,5 @@ TEMPORARY_ICS_ID = 'ZZ'
 # CSENTRY MAC organizationally unique identifier
 # This is a locally administered address
 MAC_OUI = '02:42:42'
+
+DOCUMENTATION_URL = 'http://ics-infrastructure.pages.esss.lu.se/csentry/index.html'

app/templates/base.html

@@ -29,6 +29,7 @@
           {% if current_user.is_authenticated and current_user.is_admin %}
             <a class="nav-item nav-link" href="{{ url_for('admin.index') }}">Admin</a>
           {% endif %}
+          <a class="nav-item nav-link" href="{{ config['DOCUMENTATION_URL'] }}" target="_blank">Help</a>
         </div>
         <div class="navbar-nav">
           {% if current_user.is_authenticated %}