Merge branch 'docs-bprescott-20200818-servicetemplates' into 'master'

Docs: Clarify how service templates work

See merge request gitlab-org/gitlab!39676

doc/user/project/integrations/services_templates.md

@@ -6,20 +6,52 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 # Service templates
 
-Using a service template, GitLab administrators can provide default values for configuring integrations at the project level.
+Using a service template, GitLab administrators can:
 
-When you enable a service template, the defaults are applied to **all** projects that do not
-already have the integration enabled or do not otherwise have custom values saved.
-The values are pre-filled on each project's configuration page for the applicable integration.
+- Provide default values for configuring integrations when creating new projects.
+- Bulk configure all existing projects in one step.
 
-If you disable the template, these values no longer appear as defaults, while
-any values already saved for an integration remain unchanged.
+When you enable a service template:
+
+- The defaults are applied to **all** existing projects that either:
+  - Don't already have the integration enabled.
+  - Don't have custom values stored for already enabled integrations.
+- Values are populated on each project's configuration page for the applicable
+  integration.
+- Settings are stored at the project level.
+
+If you disable the template:
+
+- GitLab default values again become the default values for integrations on
+  new projects.
+- Projects previously configured using the template will continue to use
+  those settings.
+
+If you change the template, the revised values are applied to new projects. This feature
+does not provide central administration of integration settings.
+
+## Central administration of project integrations
+
+A new set of features is being introduced in GitLab to provide more control over
+how integrations are configured at the instance, group, and project level.
+
+[Read more about setting up project integration management](../../admin_area/settings/project_integration_management.md)
+(introduced in GitLab 13.3) and [our plans for managing integrations](https://gitlab.com/groups/gitlab-org/-/epics/2137).
 
 ## Enable a service template
 
 Navigate to the **Admin Area > Service Templates** and choose the service
 template you wish to create.
 
+Recommendation:
+
+- Test the settings on some projects individually before enabling a template.
+- Copy the working settings from a project to the template.
+
+There is no "Test settings" option when enabling templates. If the settings do not work,
+these incorrect settings will be applied to all existing projects that do not already have
+the integration configured. Fixing the integration then needs to be done project-by-project.
+
 ## Service for external issue trackers
 
 The following image shows an example service template for Redmine.