Add suggestions from code review

Author: johannaengland

docs/about-argus.rst

@@ -67,7 +67,7 @@ server, such as:
 * Administration of Argus user accounts
 * Creating API authentication tokens for users
 * Defining new source systems to collect incidents from
-* Creating and update planned maintenance tasks
+* Creating and updating planned maintenance tasks
 
 Pick and choose
 ---------------

docs/reference/models.rst

@@ -96,9 +96,11 @@ Handling maintenance work
 
    PlannedMaintenanceTask
       Holds the user a task is created by, when it was created, which is set
-      automatically, the start and end time of such a task and a description of what
-      this maintenance work entails or why it is happening.
-      It also holds a collection of ``Filter``\s that describe what kind of events are covered by the planned maintenance in question.
+      automatically. Also holds the start and end time of such a task and a description
+      of what this maintenance work entails or why it is happening.
+
+      It also holds a collection of ``Filter``\s that describe what kind of events are
+      covered by that planned maintenance.
 
 ER diagram
 ==========

docs/reference/planned-maintenance.rst

@@ -2,20 +2,22 @@
 Planned maintenance
 ===================
 
-To interact with planned maintenance tasks visit the admin interface at
+To interact with planned maintenance tasks visit the admin interface at:
 ``/admin/argus_plannedmaintenance/plannedmaintenancetask/``.
 
 A planned maintenance task consists of a start time and an end time (where the latter
-is by default infinity). Those define the period during which planned work is happening and
-when notifications for events, for example for affected devices, should not be sent.
+is by default infinity). Those define the period during which planned work is happening
+and when notifications for events, for example for affected devices, should not be
+sent.
 
-Filters are used to define exactly for which kind of events notifications should be
-suppressed. As it is for notification profiles, if multiple filters are connected to
-one planned maintenance task, then that tasks will only lead to a notification being
+Filters are used to define exactly which kind of events notifications should be
+suppressed for. As it is for notification profiles, if multiple filters are connected
+to one planned maintenance task, then that tasks will only lead to a notification being
 suppressed if all of the filters apply to that event.
 
 .. warning:: When notifications are suppressed during a planned maintenance task and
-    that task ends while the incident is still open, you will not receive a notification.
+    that task ends, while the incident is still open, you will not receive a
+    notification.
     It is your responsibility to check that everything is resolved when a planned
     maintenance task is finished!
 
@@ -35,7 +37,7 @@ Adding/editing a planned maintenance task
 
 If you want to add a planned maintenance task click the
 ``Add planned maintenance task`` button. If you want to see details for a specific
-tasks or edit it click the username in the column ``created by``.
+task or edit it, click the username in the column ``created by``.
 
-You can mark an existing task as finished and see it's history by clicking on the
+You can mark an existing task as finished and see its history by clicking on the
 buttons in the top right corner of the edit page.