Add option to set exact backup times

Change-Id: Ic43b0f4c77c5d25551ea32e0cac3d9958beb2b8d
diff --git a/README.rst b/README.rst
index 1829485..a7e0b72 100644
--- a/README.rst
+++ b/README.rst
@@ -73,6 +73,46 @@
   default location, same on both client and server side.
 
 
+Backup client at exact times:
+
+..code-block:: yaml
+
+  xtrabackup:
+    client:
+      enabled: true
+      full_backups_to_keep: 3
+      incr_before_full: 3
+      backup_dir: /var/backups/mysql/xtrabackup
+      backup_times:
+        dayOfWeek: 0
+        hour: 4
+        minute: 52
+      compression: true
+      compression_threads: 2
+      database:
+        user: user
+        password: password
+      target:
+        host: host01
+
+  .. note:: Parameters in ``backup_times`` section can be used to set up exact
+  time the cron job should be executed. In this example, the backup job
+  would be executed every Sunday at 4:52 AM. If any of the individual
+  ``backup_times`` parameters is not defined, the defalut ``*`` value will be
+  used. For example, if minute parameter is ``*``, it will run the backup every minute,
+  which is ususally not desired.
+  Available parameters are ``dayOfWeek``, ``dayOfMonth``, ``month``, ``hour`` and ``minute``.
+  Please see the crontab reference for further info on how to set these parameters.
+
+  .. note:: Please be aware that only ``backup_times`` section OR
+  ``hours_before_full(incr)`` can be defined. If both are defined, The
+  ``backup_times`` section will be peferred.
+
+  .. note:: New parameter ``incr_before_full`` needs to be defined. This
+  number sets number of incremental backups to be run, before a full backup
+  is performed.
+
+
 Backup server rsync and non-default backup directory:
 
 .. code-block:: yaml
@@ -102,6 +142,42 @@
       server:
         restrict_clients: false
 
+
+Backup server at exact times:
+
+..code-block:: yaml
+
+  xtrabackup:
+    server:
+      enabled: true
+      full_backups_to_keep: 3
+      incr_before_full: 3
+      backup_dir: /srv/backup
+      backup_times:
+        dayOfWeek: 0
+        hour: 4
+        minute: 52
+      key:
+        xtrabackup_pub_key:
+          enabled: true
+          key: key
+
+  .. note:: Parameters in ``backup_times`` section can be used to set up exact
+  time the cron job should be executed. In this example, the backup job
+  would be executed every Sunday at 4:52 AM. If any of the individual
+  ``backup_times`` parameters is not defined, the defalut ``*`` value will be
+  used. For example, if minute parameter is ``*``, it will run the backup every minute,
+  which is ususally not desired.
+  Please see the crontab reference for further info on how to set these parameters.
+
+  .. note:: Please be aware that only ``backup_times`` section OR
+  ``hours_before_full(incr)`` can be defined. If both are defined, The
+  ``backup_times`` section will be peferred.
+
+  .. note:: New parameter ``incr_before_full`` needs to be defined. This
+  number sets number of incremental backups to be run, before a full backup
+  is performed.
+
 Client restore from local backups:
 
 .. code-block:: yaml