maintenance: add verification and prune to section

Includes new screen shots of interface

Signed-off-by: Dylan Whyte <d.whyte@proxmox.com>

docs/maintenance.rst

@@ -1,13 +1,60 @@
 Maintenance Tasks
 =================
 
-Garbage Collection
+Pruning & Garbage Collection
-------------------
+----------------------------
+
+Pruning can be scheduled on both a backup group and a datastore level. To access
+pruning functionality for a specific backup group, you can use the prune command
+line option discussed in :ref:`backup-pruning`, or navigate to the **Content**
+tab of the datastore and click the scissors icon in the **Actions** column of
+the relevant backup group. To prune on a datastore level, scheduling options can
+be found under the **Prune & GC** tab of the datastore. Here you can set
+retention settings and edit the interval at which pruning takes place.
+
+.. image:: images/screenshots/pbs-gui-datastore-prunegc.png
+  :align: right
+  :alt: Prune and garbage collection options
 
 You can monitor and run :ref:`garbage collection <garbage-collection>` on the
 Proxmox Backup Server using the ``garbage-collection`` subcommand of
-``proxmox-backup-manager``. You can use the ``start`` subcommand to manually start garbage
+``proxmox-backup-manager``. You can use the ``start`` subcommand to manually
-collection on an entire datastore and the ``status`` subcommand to see
+start garbage collection on an entire datastore and the ``status`` subcommand to
-attributes relating to the :ref:`garbage collection <garbage-collection>`.
+see attributes relating to the :ref:`garbage collection <garbage-collection>`.
 
-.. todo:: Add section on verification
+This functionality can also be accessed in the GUI, by navigating to **Prune &
+GC** from the top panel. From here, you can edit the schedule at which garbage
+collection runs and manually start the operation.
+
+
+.. _verification:
+
+Verification
+------------
+
+.. image:: images/screenshots/pbs-gui-datastore-verifyjob-add.png
+  :align: right
+  :alt: Adding a verify job
+
+Proxmox Backup offers various verification options to ensure that backup data is
+intact.  Verification is generally carried out through the creation of verify
+jobs. These are scheduled tasks that run verification at a given interval (see
+:ref:`calendar-events`). With these, you can set whether already verified
+snapshots are ignored, as well as set a time period, after which verified jobs
+are checked again. The interface for creating verify jobs can be found under the
+**Verify Jobs** tab of the datastore.
+
+.. Note:: It is recommended that you reverify all backups at least monthly, even
+  if a previous verification was successful. This is becuase physical drives
+  are susceptible to damage over time, which can cause an old, working backup
+  to become corrupted in a process known as `bit rot/data degradation
+  <https://en.wikipedia.org/wiki/Data_degradation>`_. It is good practice to
+  have a regularly recurring (hourly/daily) verification job, which checks new
+  and expired backups, then another weekly/monthly job that will reverify
+  everything. This way, there will be no surprises when it comes to restoring
+  data.
+
+Aside from using verify jobs, you can also run verification manually on entire
+datastores, backup groups, or snapshots. To do this, navigate to the **Content**
+tab of the datastore and either click *Verify All*, or select the *V.* icon from
+the *Actions* column in the table.