[ADD] helpdesk: doc about SLA (#647)

helpdesk/overview.rst

@@ -5,4 +5,5 @@ Overview
 .. toctree::
    :titlesonly:
 
-   overview/getting_started
+   overview/getting_started
+   overview/sla

helpdesk/overview/sla.rst

@@ -0,0 +1,44 @@
+==============================
+Service Level Agreements (SLA)
+==============================
+
+Service Level Agreements (SLA) are commitments you make with your customers to outline how a
+service is delivered. It bolsters trust between you and your customers as it makes clear what
+needs to be done, to what standard, and when.
+
+Create your policies
+====================
+
+| First, enable the feature on the settings of the team you would like policies to be applied,
+  going to :menuselection:`Helpdesk --> Configuration --> Helpdesk Teams`.
+| Create your policies through the team’s settings page or go to :menuselection:`Helpdesk -->
+  Configuration --> SLA Policies`.
+
+.. image:: media/new_sla.png
+   :align: center
+   :height: 340
+   :alt: View of an SLA form in Odoo Helpdesk
+
+| Choose to which **Team** the policy is relevant and the **Minimum Priority** a ticket needs to
+  have for the policy to be applied.
+| **Target** is the stage a ticket needs to reach within the period defined to satisfy the
+  SLA. The period is based on the ticket’s creation date, and a deadline is set on the ticket’s form
+  once it matches an SLA policy rule. If a ticket has more than one policy applied to it, the
+  closest deadline of all SLAs is the one considered.
+| When a ticket has satisfied an SLA policy, the SLA tag appears in green and the deadline field
+  is not shown anymore.
+
+.. image:: media/ticket_green_tag.png
+   :align: center
+   :height: 330
+   :alt: View of a ticket’s form emphasizing a satisfied SLA in Odoo Helpdesk
+
+SLA Analysis
+============
+
+Go to :menuselection:`Helpdesk --> Reporting --> SLA Status Analysis`. Apply *Filters* and
+*Group by* to identify tickets that should be prioritized and keep track of upcoming deadlines.
+
+.. image:: media/sla_analysis.png
+   :align: center
+   :alt: View of the SLA status analysis page emphasizing the group by option in Odoo Helpdesk