docs: admin and journalist guide regarding daily notifications

docs/install.rst

@@ -69,6 +69,15 @@ continuing:
    can add more later)
 -  The username of the system admin
 
+You can also, optionally, require that :doc:`daily notifications about
+the number of submissions <journalist>` received in the past 24h are
+sent via email so journalists know if it is worth checking the
+*Journalist Interface*. For this you will need:
+
+-  The Journalist Alert Key
+-  The Journalist Alert Key fingerprint
+-  The email address that will receive the daily notifications
+
 You will have to copy the following required files to
 ``install_files/ansible-base``:
 

docs/journalist.rst

@@ -57,6 +57,26 @@ Journalist Interface <yubikey_setup>`.)
 
 |Journalist Interface Login|
 
+Receiving daily notifications about submissions
+-----------------------------------------------
+
+When a SecureDrop has little activity and receives only a few
+submissions every other week, checking the *Journalist Interface*
+daily only to find nothing is waiting is a burden. It is more
+convenient for journalists to be notified daily via email about the
+number of submissions received in the past 24h.
+
+If the email shows submissions were received, the journalist can
+connect to the *Journalist Interface* to get it.
+
+This is an optional feature that must be activated :doc:`by the
+administrator <admin>`. In the simplest case a journalist provides
+her/his email and GPG public key to the admin. If a team of journalist
+want to receive these daily notifications, they should share a GPG
+public key and ask the admin to setup a mail alias (SecureDrop does
+not provide that) so they all receive the daily notificaitons and are
+able to decrypt them.
+
 Interacting With Sources
 ------------------------