[DOC] Document Tempo Operator Monolithic mode (#3474)

* [DOC] Document Tempo Operator Monolithic mode

Signed-off-by: Andreas Gerstmayr <agerstmayr@redhat.com>

* clarify supported storages

Signed-off-by: Andreas Gerstmayr <agerstmayr@redhat.com>

* fix case of title

Signed-off-by: Andreas Gerstmayr <agerstmayr@redhat.com>

* Apply suggestions from code review

* Apply suggestions from code review

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Signed-off-by: Andreas Gerstmayr <agerstmayr@redhat.com>
Co-authored-by: Kim Nylander <104772500+knylander-grafana@users.noreply.github.com>

docs/sources/tempo/setup/operator/monolithic.md

@@ -0,0 +1,47 @@
+---
+title: Monolithic deployment
+description: Set up a Tempo deployment in monolithic mode
+menuTitle: Monolithic deployment
+weight: 500
+aliases:
+- /docs/tempo/operator/monolithic
+---
+
+# Monolithic deployment
+
+The `TempoMonolithic` Custom Resource (CR) creates a Tempo deployment in [Monolithic mode](https:grafana.com/docs/tempo/<TEMPO_VERSION>/setup/deployment/#monolithic-mode).
+In this mode, all components of the Tempo deployment (compactor, distributor, ingester, querier and query-frontend) are contained in a single container.
+
+This type of deployment is ideal for small deployments, demo and test setups, and supports storing traces in memory, in a Persistent Volume and in object storage.
+
+{{< admonition type="note" >}}
+The monolithic deployment of Tempo does not scale horizontally. If you require horizontal scaling, please use the `TempoStack` CR for a Tempo deployment in [Microservices mode](https://grafana.com/docs/tempo/<TEMPO_VERSION>/setup/deployment/#microservices-mode).
+{{< /admonition >}}
+## Quickstart
+
+The following manifest creates a Tempo monolithic deployment with trace ingestion over OTLP/gRPC and OTLP/HTTP, storing traces in a 2 GiB tmpfs volume (in-memory storage).
+
+```yaml
+apiVersion: tempo.grafana.com/v1alpha1
+kind: TempoMonolithic
+metadata:
+  name: sample
+spec:
+  storage:
+    traces:
+      backend: memory
+      size: 2Gi
+```
+
+Once the pod is ready, you can send traces to `tempo-sample:4317` (OTLP/gRPC) and `tempo-sample:4318` (OTLP/HTTP) inside the cluster.
+
+To configure a Grafana data source, use the URL `http://tempo-sample:3200` (available inside the cluster).
+
+## CRD Specification
+A manifest with all available configuration options is available here: [tempo.grafana.com_tempomonolithics.yaml](https://github.com/grafana/tempo-operator/blob/main/docs/spec/tempo.grafana.com_tempomonolithics.yaml).
+
+{{< admonition type="note" >}}
+This file is auto-generated and does not constitute a valid CR.
+{{< /admonition >}}
+
+It provides an overview of the structure, the available configuration options and help texts.