Include SSO Session duration documentation

Author: jameshill

images/docs/integrations/sso/session_duration/configure_session_duration.png

@@ -54,6 +54,26 @@ If you are the administrator of an organization within Buildkite with an existin
 
 If you'd like to have some help with the migration, contact [email protected].
 
+## SSO Session Duration
+
+You can configure the SSO Session Duration to timeout after a predetermined time.
+
+When the specified duration elapses, the user will be signed out of the session.
+
+To set the Session Duration you first need to select the SSO Provider you would
+like to configure.
+
+<%= image "session_duration/select_provider.png", width: 1201/2, height: 786/2, alt: "Screenshot of the Buildkite SSO Settings Page" %>
+
+Then click "Update Session Duration" from the Session Duration section of the
+SSO Provider settings page.
+
+<%= image "session_duration/update_session_duration.png", width: 1201/2, height: 1043/2, alt: "Screenshot of the Buildkite SSO Settings Page" %>
+
+You can configure the session duration to any timeout between 6 hours and 8760 hours (1 year).
+
+<%= image "session_duration/configure_session_duration.png", width: 623, height: 315, alt: "Screenshot of the Buildkite SSO Session Duration Configuration" %>
+
 ## Frequently asked questions
 
 ### Can some people in the organization use SSO and others not?