api: Touch-up comments on AgentRequest (#1143)

I think the comments were just never updated when the autoscaler-agent
was moved from a per-pod sidecar to a per-node daemonset.

Found this while working on some background work for #995.

pkg/api/types.go

@@ -172,15 +172,17 @@ func (v PluginProtoVersion) IncludesExtendedMetrics() bool {
 	return v < PluginProtoV5_0
 }
 
-// AgentRequest is the type of message sent from an autoscaler-agent to the scheduler plugin
+// AgentRequest is the type of message sent from an autoscaler-agent to the scheduler plugin on
+// behalf of a Pod on the agent's node.
 //
 // All AgentRequests expect a PluginResponse.
 type AgentRequest struct {
 	// ProtoVersion is the version of the protocol that the autoscaler-agent is expecting to use
 	//
 	// If the scheduler does not support this version, then it will respond with a 400 status.
 	ProtoVersion PluginProtoVersion `json:"protoVersion"`
-	// Pod is the namespaced name of the pod making the request
+	// Pod is the namespaced name of the Pod that the autoscaler-agent is making the request on
+	// behalf of.
 	Pod util.NamespacedName `json:"pod"`
 	// ComputeUnit gives the value of the agent's configured compute unit to use for the VM.
 	//