[release-v0.36] docs: pin version to removed folders (#6096)

As part of #6077, folders referenced by older versions of documentation
will no longer work when pointing to the main branch. These links are
now being pinned to the agent version that the versioned documentation
is associated with.

docs/sources/_index.md

@@ -7,6 +7,8 @@ canonical: https://grafana.com/docs/agent/latest/
 title: Grafana Agent
 description: Grafana Agent is a flexible, performant, vendor-neutral, telemetry collector
 weight: 350
+cascade:
+  AGENT_RELEASE: v0.36.0
 ---
 
 # Grafana Agent

docs/sources/static/set-up/install/install-agent-kubernetes.md

@@ -16,9 +16,9 @@ To deploy Grafana Agent in static mode on Kubernetes, perform the following step
 
 1. Download one of the following manifests from GitHub and save it as `manifest.yaml`:
 
-   - Metric collection (StatefulSet): [agent-bare.yaml](https://github.com/grafana/agent/blob/main/production/kubernetes/agent-bare.yaml)
-   - Log collection (DaemonSet): [agent-loki.yaml](https://github.com/grafana/agent/blob/main/production/kubernetes/agent-loki.yaml)
-   - Trace collection (Deployment): [agent-traces.yaml](https://github.com/grafana/agent/blob/main/production/kubernetes/agent-traces.yaml)
+   - Metric collection (StatefulSet): [agent-bare.yaml](https://github.com/grafana/agent/blob/{{< param "AGENT_RELEASE" >}}/production/kubernetes/agent-bare.yaml)
+   - Log collection (DaemonSet): [agent-loki.yaml](https://github.com/grafana/agent/blob/{{< param "AGENT_RELEASE" >}}/production/kubernetes/agent-loki.yaml)
+   - Trace collection (Deployment): [agent-traces.yaml](https://github.com/grafana/agent/blob/{{< param "AGENT_RELEASE" >}}/production/kubernetes/agent-traces.yaml)
 
 1. Edit the downloaded `manifest.yaml` and replace the placeholders with information relevant to your Kubernetes deployment.