docs: add a miniature article about observability

docs/plugins/observability.md

@@ -0,0 +1,21 @@
+---
+id: observability
+title: Observability
+# prettier-ignore
+description: Adding Observability to Your Plugin
+---
+
+This article briefly describes the observability option that are available to a
+Backstage integrator.
+
+## Google Analytics
+
+There is a basic Google Analytics integration built into Backstage. You can
+enable it by adding the following to your app configuration:
+
+```yaml
+app:
+  googleAnalyticsTrackingId: UA-000000-0
+```
+
+Replace the tracking ID with your own.

microsite/sidebars.json

@@ -129,7 +129,8 @@
         "ids": [
           "plugins/publishing",
           "plugins/publish-private",
-          "plugins/add-to-marketplace"
+          "plugins/add-to-marketplace",
+          "plugins/observability"
         ]
       }
     ],

mkdocs.yml

@@ -80,6 +80,7 @@ nav:
       - Publishing:
           - Open source and npm: 'plugins/publishing.md'
           - Private/internal (non-open source): 'plugins/publish-private.md'
+          - Observability: 'plugins/observability.md'
   - Configuration:
       - Overview: 'conf/index.md'
       - Reading Configuration: 'conf/reading.md'