docs: update references to renamed commons repository (#11)

services/docs/content/en/root/reference/_index.md

@@ -0,0 +1,11 @@
+---
+title: Reference
+description: API and technical references for developers.
+weight: 30
+---
+
+Technical reference materials and APIs for the Root framework.
+
+{{% cards %}}
+{{< card link="root-api" title="ROOT_ API reference" icon="code" subtitle="Standardized environment variables and logging helpers." >}}
+{{% /cards %}}