add docs

docs/en/Administrator/sessions.rst

@@ -0,0 +1,26 @@
+Session issues
+==============
+
+If you end up disconnected even while checking the *Stay signed in
+checkbox*, please run the following commands as root (or with sudo) :
+
+::
+
+    mkdir /var/lib/wallabag-sessions
+    chown www-data:www-data /var/lib/wallabag-sessions
+
+*NOTE : The www-data user and group may not exist, you may use
+``chown http:http /var/lib/wallabag-sessions`` instead*
+
+Then, using apache add:
+``php_admin_value session.save_path /var/lib/wallabag-sessions`` to your
+apache vhost, for instance ``wallabag-apache.conf`` Finally, restart
+apache, for instance like this : ``/etc/init.d/apache2 restart``
+
+If you’re using nginx, add
+``php_admin_value[session.save_path] = /var/lib/wallabag-sessions`` in
+your nginx configuration file. Then, restart nginx :
+``/etc/init.d/nginx restart``
+
+*NOTE : If you’re using systemd, you should do
+``systemctl restart apache2`` (or nginx).*