[release-12.1.0] Docs: What's new, Upgrade guide, and breaking changes v12.1 (#108540)

Co-authored-by: Jacob Valdez <jacob.valdez@grafana.com>
Co-authored-by: Robby Milo <robbymilo@fastmail.com>

docs/sources/upgrade-guide/upgrade-v12.1/index.md

@@ -0,0 +1,22 @@
+---
+description: Guide for upgrading to Grafana v12.1
+keywords:
+  - grafana
+  - configuration
+  - documentation
+  - upgrade
+  - '12.1'
+title: Upgrade to Grafana v12.1
+menuTitle: Upgrade to v12.1
+weight: 499
+---
+
+# Upgrade to Grafana v12.1
+
+{{< docs/shared lookup="upgrade/intro_2.md" source="grafana" version="<GRAFANA_VERSION>" >}}
+
+{{< docs/shared lookup="back-up/back-up-grafana.md" source="grafana" version="<GRAFANA_VERSION>" leveloffset="+1" >}}
+
+{{< docs/shared lookup="upgrade/upgrade-common-tasks.md" source="grafana" version="<GRAFANA_VERSION>" >}}
+
+## Technical notes